DOI: 10.1038/srep12285. Electronic, Dielectric and Plasmonic Properties of Two-Dimensional Electride Materials X2N (X=Ca, Sr): A First-Principles Study

Electronic, Dielectric and Plasmonic Properties of Two-Dimensional Electride Materials X2N (X=Ca, Sr): A First-Principles Study

10.1038/srep12285

Crossref journal-article

Springer Science and Business Media LLC

Scientific Reports (297)

Abstract

AbstractBased on first-principles calculations, we systematically study the electronic, dielectric and plasmonic properties of two-dimensional (2D) electride materials X2N (X = Ca, Sr). We show that both Ca2N and Sr2N are stable down to monolayer thickness. For thicknesses larger than 1-monolayer (1-ML), there are 2D anionic electron layers confined in the regions between the [X2N]+ layers. These electron layers are strongly trapped and have weak coupling between each other. As a result, for the thickness dependence of many properties such as the surface energy, work function and dielectric function, the most dramatic change occurs when going from 1-ML to 2-ML. For both bulk and few-layer Ca2N and Sr2N, the in-plane and out-of-plane real components of their dielectric functions have different signs in an extended frequency range covering the near infrared, indicating their potential applications as indefinite media. We find that bulk Ca2N and Sr2N could support surface plasmon modes in the near infrared range. Moreover, tightly-bounded plasmon modes could exist in their few-layer structures. These modes have significantly shorter wavelengths (few tens of nanometers) compared with that of conventional noble metal materials, suggesting their great potential for plasmonic devices with much smaller dimensions.

Bibliography

Guan, S., Yang, S. A., Zhu, L., Hu, J., & Yao, Y. (2015). Electronic, Dielectric and Plasmonic Properties of Two-Dimensional Electride Materials X2N (X=Ca, Sr): A First-Principles Study. Scientific Reports, 5(1).

Authors 5

Shan Guan (first)
Shengyuan A. Yang (additional)
Liyan Zhu (additional)
Junping Hu (additional)
Yugui Yao (additional)

References 53 Referenced 80

Dye, J. L. Electrons as Anions. Science 301, 607–608 (2003). (10.1126/science.1088103) / Science by JL Dye (2003)
Dye, J. L. Electrides: early examples of quantum confinement. Acc.Chem.Res. 42, 1564–1572 (2009). (10.1021/ar9000857) / Acc.Chem.Res. by JL Dye (2009)
Ellaboudy, A., Dye, J. L. & Smith, P. B. Cesium 18-Crown-6 Compounds. A Crystalline Ceside and a Crystalline Electride. J. Am. Chem. Soc. 105, 6490–6491 (1983). (10.1021/ja00359a022) / J. Am. Chem. Soc. by A Ellaboudy (1983)
Huang, R. H., Faber, M. K., Moeggenborg, K. J., Ward, D. L. & Dye, J. L. Structure of K+ (cryptand[2.2.2J) electride and evidence for trapped electron pairs. Nature 331, 599–601 (1988). (10.1038/331599a0) / Nature by RH Huang (1988)
Dye, J. L. Electrides: Ionic Salts with Electrons as the Anions. Science 247, 663–668 (1990). (10.1126/science.247.4943.663) / Science by JL Dye (1990)
Matsuishi, S. et al. High-Density Electron Anions in a Nonaporous Single Crystal: [Ca24Al28O64]4+(4e−). Science 301, 626 (2003). (10.1126/science.1083842) / Science by S Matsuishi (2003)
Li, Z. Y., Yang, J. L., Hou, J. G. & Zhu, Q. S. Inorganic Electride: Theoretical Study on Structural and Electronic Properties. J. Am. Chem. Soc. 125, 6050–6051 (2003). (10.1021/ja034020n) / J. Am. Chem. Soc. by ZY Li (2003)
Toda, Y., Yanagi, H., Ikenaga, E., Kim, J. J., Kobata, M., Ueda, S., Kamiya, T., Hirano, M., Kobayashi, K. & Hosono, H. Work Function of a Room-Temperature, Stable Electride [Ca24Al28O64]4+(e−)4 . Adv. Mater 19, 3564–3569 (2007). (10.1002/adma.200700663) / Adv. Mater by Y Toda (2007)
Kim, S. W. & Hosono, H. Synthesis and Properties of 12CaO·7Al2O3 Electride: Review of Single Crystal and Thin Film Growth. Philos. Mag. 92, 2596 (2012). (10.1080/14786435.2012.685770) / Philos. Mag. by SW Kim (2012)
Fang, C. M., de Wijs, G. A., de Groot, R. A., Hintzen, H. T. & de With, G. Bulk and Surface Electronic Structure of the Layered Sub-Nitrides Ca2N and Sr2N. Chem. Mater 12, 1847–1852 (2000). (10.1021/cm0010102) / Chem. Mater by CM Fang (2000)
Kitano, M., Inoue, Y., Yamazaki, Y., Hayashi, F., Kanbara, S., Matsuishi, S., Yokoyama, T., Kim, S. W., Hara, M. & Hosono, H. Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store. Nat Chem 4, 934–940 (2012). (10.1038/nchem.1476) / Nat Chem by M Kitano (2012)
Pickard, C. J. & Needs, R. J. Aluminium at Terapascal Pressures. Nat. Mater 9, 624 (2010). (10.1038/nmat2796) / Nat. Mater by CJ Pickard (2010)
Gatti, M., Tokatly, I. V. & Rubio, A. Sodium: A Charge-Transfer Insulator at High Pressures. Phys. Rev. Lett. 104, 216404 (2010). (10.1103/PhysRevLett.104.216404) / Phys. Rev. Lett. by M Gatti (2010)
Miao, M.-S. & Hoffmann, R. High Pressure Electrides: A Predicative Chemical and Physical Theory. Acc. Chem. Res. 47, 1311 (2014). (10.1021/ar4002922) / Acc. Chem. Res. by M-S Miao (2014)
Lee, K., Kim, S. W., Toda, Y., Matsuishi, S & Hosono, H. Dicalcium nitride as a two-dimensional electride with an anionic electron layer. Nature 494, 336–340 (2013). (10.1038/nature11812) / Nature by K Lee (2013)
Inoshita, T., Jeong, S., Hamada, N. & Hosono, H. Exploration for Two-Dimensional Electrides via Database Screening and Ab Initio Calculation. Phys. Rev. X 4, 031023 (2014). / Phys. Rev. X by T Inoshita (2014)
Tada, T., Takemoto, S., Matsuishi, S. & Hosono, H. High-Throughput ab Initio Screening for Two-Dimensional Electride Materials. Inorg. Chem. 53, 10347–10358 (2014). (10.1021/ic501362b) / Inorg. Chem. by T Tada (2014)
Walsh, A. & Scanlon, D. Electron excess in alkaline earth sub-nitrides: 2D electron gas or 3D electride? J. Mater. Chem. C 1, 3525–3528 (2013). (10.1039/c3tc30690a) / J. Mater. Chem. C by A Walsh (2013)
Zhao, S. T., Li, Z. Y. & Yang, J. L. Obtaining two-dimensional electron gas in free space without resorting to electron doping: an electride based design. J. Am. Chem. Soc. 136, 13313–13318 (2014). (10.1021/ja5065125) / J. Am. Chem. Soc. by ST Zhao (2014)
Smith, D. R. & Schurig, D. Electromagnetic Wave Propagation in Media with Indefinite Permittivity and Permeability Tensors. Phys. Rev. Lett. 90, 077405 (2003). (10.1103/PhysRevLett.90.077405) / Phys. Rev. Lett. by DR Smith (2003)
Gregory, D. H., Bowman, A., Baker, C. F. & Weston, D. P. Dicalcium Nitride, Ca2N-a 2D “Excess Electron” Compound: Synthetic Routes and Crystal Chemistry. J. Mater. Chem. 10, 1635 (2000). (10.1039/b001911i) / J. Mater. Chem. by DH Gregory (2000)
Baker, C. F., Barker, M. G. & Blake, A. J. Calcium nitride (Ca2N), a redetermination. Acta Cryst. E57, i6–i7 (2001). / Acta Cryst. by CF Baker (2001)
Reckeweg, O. & DiSalvo, F. J. Alkaline earth metal nitride compounds with the composition M2NX (M = Ca, Sr, Ba; X = ◻, H, Cl or Br). Solid State Sciences 4, 575–584 (2002). (10.1016/S1293-2558(02)01300-6) / Solid State Sciences by O Reckeweg (2002)
Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J Comput Chem. 27, 1787 (2006). (10.1002/jcc.20495) / J Comput Chem. by S Grimme (2006)
Zabel, H. Phonons in layered compounds. J. Phys. Condens. Matter 13, 7679 (2001). (10.1088/0953-8984/13/34/313) / J. Phys. Condens. Matter by H Zabel (2001)
Liu, F., Ming, P. & Li, J. Ab initio calculation of ideal strength and phonon instability of graphene under tension. Phys. Rev. B 76, 046120 (2007). (10.1103/PhysRevE.76.046120) / Phys. Rev. B by F Liu (2007)
Molina-Sanchez, A. & Wirtz, L. Phonons in single-layer and few-layer MoS2 and WS2 . Phys. Rev. B 84, 155413 (2011). (10.1103/PhysRevB.84.155413) / Phys. Rev. B by A Molina-Sanchez (2011)
Zhu, L., Zhang, G. & Li, B. Coexistence of size-dependent and size-independent thermal conductivities in phosphorene. Phys. Rev. B 90, 214302 (2014). (10.1103/PhysRevB.90.214302) / Phys. Rev. B by L Zhu (2014)
Zacharia, R., Ulbricht, H. & Hertel, T. Interlayer cohesive energy of graphite from thermal desorption of polyaromatic hydrocarbons. Phys. Rev. B 69, 155406 (2004). (10.1103/PhysRevB.69.155406) / Phys. Rev. B by R Zacharia (2004)
Becke, A. D. & Edgecombe, K. E. A simple measure of electron localization in atomic and molecular systems. The Journal of Chemical Physics 92, 5397–5403 (1990). (10.1063/1.458517) / The Journal of Chemical Physics by AD Becke (1990)
Silvi, B. & Savin, A. Classification of chemical bonds based on topological analysis of electron localization functions. Nature 371, 683–686 (1994). (10.1038/371683a0) / Nature by B Silvi (1994)
Uijttewaal, M. A., Wijs, G. A. de. & Groot, R. A. de. Low work function of the (1000) Ca2N surface. J. Appl. Phys. 96, 1751–1753 (2004). (10.1063/1.1767611) / J. Appl. Phys. by MA Uijttewaal (2004)
Harl, J., Kresse, G., Sun, L. D., Hohage, M. & Zeppenfeld, L. Ab initio reflectance difference spectra of the bare and adsorbate covered Cu(110) surfaces. Phys. Rev. B 76, 035436 (2007). (10.1103/PhysRevB.76.035436) / Phys. Rev. B by J Harl (2007)
Harl, J. The linear response function in density functional theory: Optical spectra and improved description of the electron correlation. Ph.D Dissertation submitted to Universitat Wien (2008).
He, Y. & Zeng, T. First-principle study and model of dielectric functions of silver nanoparticles. J. Phys. Chem. C 114 (42), 18023–18030 (2010). (10.1021/jp101598j) / J. Phys. Chem. C by Y He (2010)
Glantschnig, K. & Ambrosch-Draxl, C. Relativistic effects on the linear optical properties of Au, Pt, Pb and W. New J. Phys. 12, 103048 (2010). (10.1088/1367-2630/12/10/103048) / New J. Phys. by K Glantschnig (2010)
Yan, J., Jacobsen, K. W. & Thygesen, K. Y. First principles study of surface plasmons on Ag(111) and H/Ag(111). Phys. Rev. B 84, 235430 (2011). (10.1103/PhysRevB.84.235430) / Phys. Rev. B by J Yan (2011)
Laref, S., Cao, J. R., Asaduzzaman, A., Runge, K., Deymier, P., Ziolkowski, R. W., Miyawaki, M. & Muralidharan, K. Size-dependent permittivity and intrinsic optical anisotropy of nanometric gold thin films: a density functional theory study. Opt. Express 21, 11827–11838 (2013). (10.1364/OE.21.011827) / Opt. Express by S Laref (2013)
Ming, W. M., Blair, S. & Liu, F. Quantum size effect on dielectric function of ultrathin metal film: a first-principles study of Al(111). J. Phys. Condens. Matter 26, 505302 (2014). (10.1088/0953-8984/26/50/505302) / J. Phys. Condens. Matter by WM Ming (2014)
Jacob, Z., Alekseyev, L. V. & Narimanov, E. Optical hyperlens: Far-field imaging beyond the diffraction limit. Opt. Express 14, 8247–8256 (2006). (10.1364/OE.14.008247) / Opt. Express by Z Jacob (2006)
Liu, Z., Lee, H., Xiong, Y., Sun, C. & Zhang, X. Far-field optical hyperlens magnifying sub-diffraction-limited objects. Science 315, 1686 (2007). (10.1126/science.1137368) / Science by Z Liu (2007)
Maier, S. A. Plasmonics: Fundamentals and Applications Springer, New York, 2007. (10.1007/0-387-37825-1)
West, P. R., Ishii, S., Naik, G. V., Emani, N. K., Shalaev, V. M. & Boltasseva, A. Searching for better plasmonics materials. Laser & Photon. Rev. 4, 795–808 (2010). (10.1002/lpor.200900055) / Laser & Photon. Rev. by PR West (2010)
Dionne, J. A., Sweatlock, L. A., Atwater, H. A. & Polman, A. Planar metal plasmon waveguides: frequency-dependent dispersion, propagation, localization and loss beyond the free electron model. Phys. Rev. B 72, 075405 (2005). (10.1103/PhysRevB.72.075405) / Phys. Rev. B by JA Dionne (2005)
Kresse, G. & Hafner, J. Ab initio molecular dynamics for open-shell transition metals. Phys. Rev. B 48, 13115–13118 (1993). (10.1103/PhysRevB.48.13115) / Phys. Rev. B by G Kresse (1993)
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169–11186 (1996). (10.1103/PhysRevB.54.11169) / Phys. Rev. B by G Kresse (1996)
Perdew, J., Burke, K. & Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 77, 3865–3868 (1996). (10.1103/PhysRevLett.77.3865) / Phys. Rev. Lett. by J Perdew (1996)
Blöchl, P. Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994). (10.1103/PhysRevB.50.17953) / Phys. Rev. B by P Blöchl (1994)
Monkhorst, H. & Pack, J. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188–5192 (1976). (10.1103/PhysRevB.13.5188) / Phys. Rev. B by H Monkhorst (1976)
Methfessel, M. & Paxton, A. High-precision sampling for Brillouin-zone integration in metals. Phys. Rev. B 40, 3616–3621 (1989). (10.1103/PhysRevB.40.3616) / Phys. Rev. B by M Methfessel (1989)
Togo, A., Oba, F. & Tanaka, I. First-principles calculations of the ferroelastic transition between rutile-type and CaCl2type SiO2 at high pressures. Phys. Rev. B 78, 134106 (2008). (10.1103/PhysRevB.78.134106) / Phys. Rev. B by A Togo (2008)
Gonze, X. & Lee, C. Y. Dynamical matrices, Born effective charges, dielectric permittivity tensors and interatomic force constants from density-functional perturbation theory. Phys. Rev. B 55, 10355–10368 (1997). (10.1103/PhysRevB.55.10355) / Phys. Rev. B by X Gonze (1997)
Nelder, J. A. & Mead, R. A Simplex Method for Function Minimization. The Computer Journal 7, 308–313 (1965). (10.1093/comjnl/7.4.308) / The Computer Journal by JA Nelder (1965)

Dates

Type	When
Created	10 years, 1 month ago (July 20, 2015, 10:26 a.m.)
Deposited	2 years, 7 months ago (Jan. 5, 2023, 9:44 a.m.)
Indexed	4 months, 4 weeks ago (March 24, 2025, 3:37 a.m.)
Issued	10 years, 1 month ago (July 20, 2015)
Published	10 years, 1 month ago (July 20, 2015)
Published Online	10 years, 1 month ago (July 20, 2015)

Funders 0

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BibTeX

@article{Guan_2015, title={Electronic, Dielectric and Plasmonic Properties of Two-Dimensional Electride Materials X2N (X=Ca, Sr): A First-Principles Study}, volume={5}, ISSN={2045-2322}, url={http://dx.doi.org/10.1038/srep12285}, DOI={10.1038/srep12285}, number={1}, journal={Scientific Reports}, publisher={Springer Science and Business Media LLC}, author={Guan, Shan and Yang, Shengyuan A. and Zhu, Liyan and Hu, Junping and Yao, Yugui}, year={2015}, month=jul }

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  "abstract": "<jats:title>Abstract</jats:title><jats:p>Based on first-principles calculations, we systematically study the electronic, dielectric and plasmonic properties of two-dimensional (2D) electride materials X<jats:sub>2</jats:sub>N (X\u2009=\u2009Ca, Sr). We show that both Ca<jats:sub>2</jats:sub>N and Sr<jats:sub>2</jats:sub>N are stable down to monolayer thickness. For thicknesses larger than 1-monolayer (1-ML), there are 2D anionic electron layers confined in the regions between the [X<jats:sub>2</jats:sub>N]<jats:sup>+</jats:sup> layers. These electron layers are strongly trapped and have weak coupling between each other. As a result, for the thickness dependence of many properties such as the surface energy, work function and dielectric function, the most dramatic change occurs when going from 1-ML to 2-ML. For both bulk and few-layer Ca<jats:sub>2</jats:sub>N and Sr<jats:sub>2</jats:sub>N, the in-plane and out-of-plane real components of their dielectric functions have different signs in an extended frequency range covering the near infrared, indicating their potential applications as indefinite media. We find that bulk Ca<jats:sub>2</jats:sub>N and Sr<jats:sub>2</jats:sub>N could support surface plasmon modes in the near infrared range. Moreover, tightly-bounded plasmon modes could exist in their few-layer structures. These modes have significantly shorter wavelengths (few tens of nanometers) compared with that of conventional noble metal materials, suggesting their great potential for plasmonic devices with much smaller dimensions.</jats:p>",
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      "author": "JL Dye",
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      "unstructured": "Dye, J. L. Electrons as Anions. Science 301, 607\u2013608 (2003).",
      "journal-title": "Science"
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    {
      "key": "BFsrep12285_CR2",
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      "first-page": "1564",
      "DOI": "10.1021/ar9000857",
      "volume": "42",
      "author": "JL Dye",
      "year": "2009",
      "unstructured": "Dye, J. L. Electrides: early examples of quantum confinement. Acc.Chem.Res. 42, 1564\u20131572 (2009).",
      "journal-title": "Acc.Chem.Res."
    },
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      "first-page": "6490",
      "DOI": "10.1021/ja00359a022",
      "volume": "105",
      "author": "A Ellaboudy",
      "year": "1983",
      "unstructured": "Ellaboudy, A., Dye, J. L. & Smith, P. B. Cesium 18-Crown-6 Compounds. A Crystalline Ceside and a Crystalline Electride. J. Am. Chem. Soc. 105, 6490\u20136491 (1983).",
      "journal-title": "J. Am. Chem. Soc."
    },
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      "key": "BFsrep12285_CR4",
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      "first-page": "599",
      "DOI": "10.1038/331599a0",
      "volume": "331",
      "author": "RH Huang",
      "year": "1988",
      "unstructured": "Huang, R. H., Faber, M. K., Moeggenborg, K. J., Ward, D. L. & Dye, J. L. Structure of K+ (cryptand[2.2.2J) electride and evidence for trapped electron pairs. Nature 331, 599\u2013601 (1988).",
      "journal-title": "Nature"
    },
    {
      "key": "BFsrep12285_CR5",
      "doi-asserted-by": "crossref",
      "first-page": "663",
      "DOI": "10.1126/science.247.4943.663",
      "volume": "247",
      "author": "JL Dye",
      "year": "1990",
      "unstructured": "Dye, J. L. Electrides: Ionic Salts with Electrons as the Anions. Science 247, 663\u2013668 (1990).",
      "journal-title": "Science"
    },
    {
      "key": "BFsrep12285_CR6",
      "doi-asserted-by": "crossref",
      "first-page": "626",
      "DOI": "10.1126/science.1083842",
      "volume": "301",
      "author": "S Matsuishi",
      "year": "2003",
      "unstructured": "Matsuishi, S. et al. High-Density Electron Anions in a Nonaporous Single Crystal: [Ca24Al28O64]4+(4e\u2212). Science 301, 626 (2003).",
      "journal-title": "Science"
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      "doi-asserted-by": "crossref",
      "first-page": "6050",
      "DOI": "10.1021/ja034020n",
      "volume": "125",
      "author": "ZY Li",
      "year": "2003",
      "unstructured": "Li, Z. Y., Yang, J. L., Hou, J. G. & Zhu, Q. S. Inorganic Electride: Theoretical Study on Structural and Electronic Properties. J. Am. Chem. Soc. 125, 6050\u20136051 (2003).",
      "journal-title": "J. Am. Chem. Soc."
    },
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      "doi-asserted-by": "crossref",
      "first-page": "3564",
      "DOI": "10.1002/adma.200700663",
      "volume": "19",
      "author": "Y Toda",
      "year": "2007",
      "unstructured": "Toda, Y., Yanagi, H., Ikenaga, E., Kim, J. J., Kobata, M., Ueda, S., Kamiya, T., Hirano, M., Kobayashi, K. & Hosono, H. Work Function of a Room-Temperature, Stable Electride [Ca24Al28O64]4+(e\u2212)4 . Adv. Mater 19, 3564\u20133569 (2007).",
      "journal-title": "Adv. Mater"
    },
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      "DOI": "10.1080/14786435.2012.685770",
      "volume": "92",
      "author": "SW Kim",
      "year": "2012",
      "unstructured": "Kim, S. W. & Hosono, H. Synthesis and Properties of 12CaO\u00b77Al2O3 Electride: Review of Single Crystal and Thin Film Growth. Philos. Mag. 92, 2596 (2012).",
      "journal-title": "Philos. Mag."
    },
    {
      "key": "BFsrep12285_CR10",
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      "first-page": "1847",
      "DOI": "10.1021/cm0010102",
      "volume": "12",
      "author": "CM Fang",
      "year": "2000",
      "unstructured": "Fang, C. M., de Wijs, G. A., de Groot, R. A., Hintzen, H. T. & de With, G. Bulk and Surface Electronic Structure of the Layered Sub-Nitrides Ca2N and Sr2N. Chem. Mater 12, 1847\u20131852 (2000).",
      "journal-title": "Chem. Mater"
    },
    {
      "key": "BFsrep12285_CR11",
      "doi-asserted-by": "crossref",
      "first-page": "934",
      "DOI": "10.1038/nchem.1476",
      "volume": "4",
      "author": "M Kitano",
      "year": "2012",
      "unstructured": "Kitano, M., Inoue, Y., Yamazaki, Y., Hayashi, F., Kanbara, S., Matsuishi, S., Yokoyama, T., Kim, S. W., Hara, M. & Hosono, H. Ammonia synthesis using a stable electride as an electron donor and reversible hydrogen store. Nat Chem 4, 934\u2013940 (2012).",
      "journal-title": "Nat Chem"
    },
    {
      "key": "BFsrep12285_CR12",
      "doi-asserted-by": "crossref",
      "first-page": "624",
      "DOI": "10.1038/nmat2796",
      "volume": "9",
      "author": "CJ Pickard",
      "year": "2010",
      "unstructured": "Pickard, C. J. & Needs, R. J. Aluminium at Terapascal Pressures. Nat. Mater 9, 624 (2010).",
      "journal-title": "Nat. Mater"
    },
    {
      "key": "BFsrep12285_CR13",
      "doi-asserted-by": "crossref",
      "first-page": "216404",
      "DOI": "10.1103/PhysRevLett.104.216404",
      "volume": "104",
      "author": "M Gatti",
      "year": "2010",
      "unstructured": "Gatti, M., Tokatly, I. V. & Rubio, A. Sodium: A Charge-Transfer Insulator at High Pressures. Phys. Rev. Lett. 104, 216404 (2010).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFsrep12285_CR14",
      "doi-asserted-by": "crossref",
      "first-page": "1311",
      "DOI": "10.1021/ar4002922",
      "volume": "47",
      "author": "M-S Miao",
      "year": "2014",
      "unstructured": "Miao, M.-S. & Hoffmann, R. High Pressure Electrides: A Predicative Chemical and Physical Theory. Acc. Chem. Res. 47, 1311 (2014).",
      "journal-title": "Acc. Chem. Res."
    },
    {
      "key": "BFsrep12285_CR15",
      "doi-asserted-by": "crossref",
      "first-page": "336",
      "DOI": "10.1038/nature11812",
      "volume": "494",
      "author": "K Lee",
      "year": "2013",
      "unstructured": "Lee, K., Kim, S. W., Toda, Y., Matsuishi, S & Hosono, H. Dicalcium nitride as a two-dimensional electride with an anionic electron layer. Nature 494, 336\u2013340 (2013).",
      "journal-title": "Nature"
    },
    {
      "key": "BFsrep12285_CR16",
      "first-page": "031023",
      "volume": "4",
      "author": "T Inoshita",
      "year": "2014",
      "unstructured": "Inoshita, T., Jeong, S., Hamada, N. & Hosono, H. Exploration for Two-Dimensional Electrides via Database Screening and Ab Initio Calculation. Phys. Rev. X 4, 031023 (2014).",
      "journal-title": "Phys. Rev. X"
    },
    {
      "key": "BFsrep12285_CR17",
      "doi-asserted-by": "crossref",
      "first-page": "10347",
      "DOI": "10.1021/ic501362b",
      "volume": "53",
      "author": "T Tada",
      "year": "2014",
      "unstructured": "Tada, T., Takemoto, S., Matsuishi, S. & Hosono, H. High-Throughput ab Initio Screening for Two-Dimensional Electride Materials. Inorg. Chem. 53, 10347\u201310358 (2014).",
      "journal-title": "Inorg. Chem."
    },
    {
      "key": "BFsrep12285_CR18",
      "doi-asserted-by": "crossref",
      "first-page": "3525",
      "DOI": "10.1039/c3tc30690a",
      "volume": "1",
      "author": "A Walsh",
      "year": "2013",
      "unstructured": "Walsh, A. & Scanlon, D. Electron excess in alkaline earth sub-nitrides: 2D electron gas or 3D electride? J. Mater. Chem. C 1, 3525\u20133528 (2013).",
      "journal-title": "J. Mater. Chem. C"
    },
    {
      "key": "BFsrep12285_CR19",
      "doi-asserted-by": "crossref",
      "first-page": "13313",
      "DOI": "10.1021/ja5065125",
      "volume": "136",
      "author": "ST Zhao",
      "year": "2014",
      "unstructured": "Zhao, S. T., Li, Z. Y. & Yang, J. L. Obtaining two-dimensional electron gas in free space without resorting to electron doping: an electride based design. J. Am. Chem. Soc. 136, 13313\u201313318 (2014).",
      "journal-title": "J. Am. Chem. Soc."
    },
    {
      "key": "BFsrep12285_CR20",
      "doi-asserted-by": "crossref",
      "first-page": "077405",
      "DOI": "10.1103/PhysRevLett.90.077405",
      "volume": "90",
      "author": "DR Smith",
      "year": "2003",
      "unstructured": "Smith, D. R. & Schurig, D. Electromagnetic Wave Propagation in Media with Indefinite Permittivity and Permeability Tensors. Phys. Rev. Lett. 90, 077405 (2003).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFsrep12285_CR21",
      "doi-asserted-by": "crossref",
      "first-page": "1635",
      "DOI": "10.1039/b001911i",
      "volume": "10",
      "author": "DH Gregory",
      "year": "2000",
      "unstructured": "Gregory, D. H., Bowman, A., Baker, C. F. & Weston, D. P. Dicalcium Nitride, Ca2N-a 2D \u201cExcess Electron\u201d Compound: Synthetic Routes and Crystal Chemistry. J. Mater. Chem. 10, 1635 (2000).",
      "journal-title": "J. Mater. Chem."
    },
    {
      "key": "BFsrep12285_CR22",
      "first-page": "i6",
      "volume": "E57",
      "author": "CF Baker",
      "year": "2001",
      "unstructured": "Baker, C. F., Barker, M. G. & Blake, A. J. Calcium nitride (Ca2N), a redetermination. Acta Cryst. E57, i6\u2013i7 (2001).",
      "journal-title": "Acta Cryst."
    },
    {
      "key": "BFsrep12285_CR23",
      "doi-asserted-by": "crossref",
      "first-page": "575",
      "DOI": "10.1016/S1293-2558(02)01300-6",
      "volume": "4",
      "author": "O Reckeweg",
      "year": "2002",
      "unstructured": "Reckeweg, O. & DiSalvo, F. J. Alkaline earth metal nitride compounds with the composition M2NX (M = Ca, Sr, Ba; X = \u25fb, H, Cl or Br). Solid State Sciences 4, 575\u2013584 (2002).",
      "journal-title": "Solid State Sciences"
    },
    {
      "key": "BFsrep12285_CR24",
      "doi-asserted-by": "crossref",
      "first-page": "1787",
      "DOI": "10.1002/jcc.20495",
      "volume": "27",
      "author": "S Grimme",
      "year": "2006",
      "unstructured": "Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J Comput Chem. 27, 1787 (2006).",
      "journal-title": "J Comput Chem."
    },
    {
      "key": "BFsrep12285_CR25",
      "doi-asserted-by": "crossref",
      "first-page": "7679",
      "DOI": "10.1088/0953-8984/13/34/313",
      "volume": "13",
      "author": "H Zabel",
      "year": "2001",
      "unstructured": "Zabel, H. Phonons in layered compounds. J. Phys. Condens. Matter 13, 7679 (2001).",
      "journal-title": "J. Phys. Condens. Matter"
    },
    {
      "key": "BFsrep12285_CR26",
      "doi-asserted-by": "crossref",
      "first-page": "046120",
      "DOI": "10.1103/PhysRevE.76.046120",
      "volume": "76",
      "author": "F Liu",
      "year": "2007",
      "unstructured": "Liu, F., Ming, P. & Li, J. Ab initio calculation of ideal strength and phonon instability of graphene under tension. Phys. Rev. B 76, 046120 (2007).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR27",
      "doi-asserted-by": "crossref",
      "first-page": "155413",
      "DOI": "10.1103/PhysRevB.84.155413",
      "volume": "84",
      "author": "A Molina-Sanchez",
      "year": "2011",
      "unstructured": "Molina-Sanchez, A. & Wirtz, L. Phonons in single-layer and few-layer MoS2 and WS2 . Phys. Rev. B 84, 155413 (2011).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR28",
      "doi-asserted-by": "crossref",
      "first-page": "214302",
      "DOI": "10.1103/PhysRevB.90.214302",
      "volume": "90",
      "author": "L Zhu",
      "year": "2014",
      "unstructured": "Zhu, L., Zhang, G. & Li, B. Coexistence of size-dependent and size-independent thermal conductivities in phosphorene. Phys. Rev. B 90, 214302 (2014).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR29",
      "doi-asserted-by": "crossref",
      "first-page": "155406",
      "DOI": "10.1103/PhysRevB.69.155406",
      "volume": "69",
      "author": "R Zacharia",
      "year": "2004",
      "unstructured": "Zacharia, R., Ulbricht, H. & Hertel, T. Interlayer cohesive energy of graphite from thermal desorption of polyaromatic hydrocarbons. Phys. Rev. B 69, 155406 (2004).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR30",
      "doi-asserted-by": "crossref",
      "first-page": "5397",
      "DOI": "10.1063/1.458517",
      "volume": "92",
      "author": "AD Becke",
      "year": "1990",
      "unstructured": "Becke, A. D. & Edgecombe, K. E. A simple measure of electron localization in atomic and molecular systems. The Journal of Chemical Physics 92, 5397\u20135403 (1990).",
      "journal-title": "The Journal of Chemical Physics"
    },
    {
      "key": "BFsrep12285_CR31",
      "doi-asserted-by": "crossref",
      "first-page": "683",
      "DOI": "10.1038/371683a0",
      "volume": "371",
      "author": "B Silvi",
      "year": "1994",
      "unstructured": "Silvi, B. & Savin, A. Classification of chemical bonds based on topological analysis of electron localization functions. Nature 371, 683\u2013686 (1994).",
      "journal-title": "Nature"
    },
    {
      "key": "BFsrep12285_CR32",
      "doi-asserted-by": "crossref",
      "first-page": "1751",
      "DOI": "10.1063/1.1767611",
      "volume": "96",
      "author": "MA Uijttewaal",
      "year": "2004",
      "unstructured": "Uijttewaal, M. A., Wijs, G. A. de. & Groot, R. A. de. Low work function of the (1000) Ca2N surface. J. Appl. Phys. 96, 1751\u20131753 (2004).",
      "journal-title": "J. Appl. Phys."
    },
    {
      "key": "BFsrep12285_CR33",
      "doi-asserted-by": "crossref",
      "first-page": "035436",
      "DOI": "10.1103/PhysRevB.76.035436",
      "volume": "76",
      "author": "J Harl",
      "year": "2007",
      "unstructured": "Harl, J., Kresse, G., Sun, L. D., Hohage, M. & Zeppenfeld, L. Ab initio reflectance difference spectra of the bare and adsorbate covered Cu(110) surfaces. Phys. Rev. B 76, 035436 (2007).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR34",
      "unstructured": "Harl, J. The linear response function in density functional theory: Optical spectra and improved description of the electron correlation. Ph.D Dissertation submitted to Universitat Wien (2008)."
    },
    {
      "issue": "42",
      "key": "BFsrep12285_CR35",
      "doi-asserted-by": "crossref",
      "first-page": "18023",
      "DOI": "10.1021/jp101598j",
      "volume": "114",
      "author": "Y He",
      "year": "2010",
      "unstructured": "He, Y. & Zeng, T. First-principle study and model of dielectric functions of silver nanoparticles. J. Phys. Chem. C 114 (42), 18023\u201318030 (2010).",
      "journal-title": "J. Phys. Chem. C"
    },
    {
      "key": "BFsrep12285_CR36",
      "doi-asserted-by": "crossref",
      "first-page": "103048",
      "DOI": "10.1088/1367-2630/12/10/103048",
      "volume": "12",
      "author": "K Glantschnig",
      "year": "2010",
      "unstructured": "Glantschnig, K. & Ambrosch-Draxl, C. Relativistic effects on the linear optical properties of Au, Pt, Pb and W. New J. Phys. 12, 103048 (2010).",
      "journal-title": "New J. Phys."
    },
    {
      "key": "BFsrep12285_CR37",
      "doi-asserted-by": "crossref",
      "first-page": "235430",
      "DOI": "10.1103/PhysRevB.84.235430",
      "volume": "84",
      "author": "J Yan",
      "year": "2011",
      "unstructured": "Yan, J., Jacobsen, K. W. & Thygesen, K. Y. First principles study of surface plasmons on Ag(111) and H/Ag(111). Phys. Rev. B 84, 235430 (2011).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR38",
      "doi-asserted-by": "crossref",
      "first-page": "11827",
      "DOI": "10.1364/OE.21.011827",
      "volume": "21",
      "author": "S Laref",
      "year": "2013",
      "unstructured": "Laref, S., Cao, J. R., Asaduzzaman, A., Runge, K., Deymier, P., Ziolkowski, R. W., Miyawaki, M. & Muralidharan, K. Size-dependent permittivity and intrinsic optical anisotropy of nanometric gold thin films: a density functional theory study. Opt. Express 21, 11827\u201311838 (2013).",
      "journal-title": "Opt. Express"
    },
    {
      "key": "BFsrep12285_CR39",
      "doi-asserted-by": "crossref",
      "first-page": "505302",
      "DOI": "10.1088/0953-8984/26/50/505302",
      "volume": "26",
      "author": "WM Ming",
      "year": "2014",
      "unstructured": "Ming, W. M., Blair, S. & Liu, F. Quantum size effect on dielectric function of ultrathin metal film: a first-principles study of Al(111). J. Phys. Condens. Matter 26, 505302 (2014).",
      "journal-title": "J. Phys. Condens. Matter"
    },
    {
      "key": "BFsrep12285_CR40",
      "doi-asserted-by": "crossref",
      "first-page": "8247",
      "DOI": "10.1364/OE.14.008247",
      "volume": "14",
      "author": "Z Jacob",
      "year": "2006",
      "unstructured": "Jacob, Z., Alekseyev, L. V. & Narimanov, E. Optical hyperlens: Far-field imaging beyond the diffraction limit. Opt. Express 14, 8247\u20138256 (2006).",
      "journal-title": "Opt. Express"
    },
    {
      "key": "BFsrep12285_CR41",
      "doi-asserted-by": "crossref",
      "first-page": "1686",
      "DOI": "10.1126/science.1137368",
      "volume": "315",
      "author": "Z Liu",
      "year": "2007",
      "unstructured": "Liu, Z., Lee, H., Xiong, Y., Sun, C. & Zhang, X. Far-field optical hyperlens magnifying sub-diffraction-limited objects. Science 315, 1686 (2007).",
      "journal-title": "Science"
    },
    {
      "key": "BFsrep12285_CR42",
      "doi-asserted-by": "crossref",
      "unstructured": "Maier, S. A. Plasmonics: Fundamentals and Applications Springer, New York, 2007.",
      "DOI": "10.1007/0-387-37825-1"
    },
    {
      "key": "BFsrep12285_CR43",
      "doi-asserted-by": "crossref",
      "first-page": "795",
      "DOI": "10.1002/lpor.200900055",
      "volume": "4",
      "author": "PR West",
      "year": "2010",
      "unstructured": "West, P. R., Ishii, S., Naik, G. V., Emani, N. K., Shalaev, V. M. & Boltasseva, A. Searching for better plasmonics materials. Laser & Photon. Rev. 4, 795\u2013808 (2010).",
      "journal-title": "Laser & Photon. Rev."
    },
    {
      "key": "BFsrep12285_CR44",
      "doi-asserted-by": "crossref",
      "first-page": "075405",
      "DOI": "10.1103/PhysRevB.72.075405",
      "volume": "72",
      "author": "JA Dionne",
      "year": "2005",
      "unstructured": "Dionne, J. A., Sweatlock, L. A., Atwater, H. A. & Polman, A. Planar metal plasmon waveguides: frequency-dependent dispersion, propagation, localization and loss beyond the free electron model. Phys. Rev. B 72, 075405 (2005).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR45",
      "doi-asserted-by": "crossref",
      "first-page": "13115",
      "DOI": "10.1103/PhysRevB.48.13115",
      "volume": "48",
      "author": "G Kresse",
      "year": "1993",
      "unstructured": "Kresse, G. & Hafner, J. Ab initio molecular dynamics for open-shell transition metals. Phys. Rev. B 48, 13115\u201313118 (1993).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR46",
      "doi-asserted-by": "crossref",
      "first-page": "11169",
      "DOI": "10.1103/PhysRevB.54.11169",
      "volume": "54",
      "author": "G Kresse",
      "year": "1996",
      "unstructured": "Kresse, G. & Furthm\u00fcller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169\u201311186 (1996).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR47",
      "doi-asserted-by": "crossref",
      "first-page": "3865",
      "DOI": "10.1103/PhysRevLett.77.3865",
      "volume": "77",
      "author": "J Perdew",
      "year": "1996",
      "unstructured": "Perdew, J., Burke, K. & Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 77, 3865\u20133868 (1996).",
      "journal-title": "Phys. Rev. Lett."
    },
    {
      "key": "BFsrep12285_CR48",
      "doi-asserted-by": "crossref",
      "first-page": "17953",
      "DOI": "10.1103/PhysRevB.50.17953",
      "volume": "50",
      "author": "P Bl\u00f6chl",
      "year": "1994",
      "unstructured": "Bl\u00f6chl, P. Projector augmented-wave method. Phys. Rev. B 50, 17953\u201317979 (1994).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR49",
      "doi-asserted-by": "crossref",
      "first-page": "5188",
      "DOI": "10.1103/PhysRevB.13.5188",
      "volume": "13",
      "author": "H Monkhorst",
      "year": "1976",
      "unstructured": "Monkhorst, H. & Pack, J. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188\u20135192 (1976).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR50",
      "doi-asserted-by": "crossref",
      "first-page": "3616",
      "DOI": "10.1103/PhysRevB.40.3616",
      "volume": "40",
      "author": "M Methfessel",
      "year": "1989",
      "unstructured": "Methfessel, M. & Paxton, A. High-precision sampling for Brillouin-zone integration in metals. Phys. Rev. B 40, 3616\u20133621 (1989).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR51",
      "doi-asserted-by": "crossref",
      "first-page": "134106",
      "DOI": "10.1103/PhysRevB.78.134106",
      "volume": "78",
      "author": "A Togo",
      "year": "2008",
      "unstructured": "Togo, A., Oba, F. & Tanaka, I. First-principles calculations of the ferroelastic transition between rutile-type and CaCl2type SiO2 at high pressures. Phys. Rev. B 78, 134106 (2008).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR52",
      "doi-asserted-by": "crossref",
      "first-page": "10355",
      "DOI": "10.1103/PhysRevB.55.10355",
      "volume": "55",
      "author": "X Gonze",
      "year": "1997",
      "unstructured": "Gonze, X. & Lee, C. Y. Dynamical matrices, Born effective charges, dielectric permittivity tensors and interatomic force constants from density-functional perturbation theory. Phys. Rev. B 55, 10355\u201310368 (1997).",
      "journal-title": "Phys. Rev. B"
    },
    {
      "key": "BFsrep12285_CR53",
      "doi-asserted-by": "crossref",
      "first-page": "308",
      "DOI": "10.1093/comjnl/7.4.308",
      "volume": "7",
      "author": "JA Nelder",
      "year": "1965",
      "unstructured": "Nelder, J. A. & Mead, R. A Simplex Method for Function Minimization. The Computer Journal 7, 308\u2013313 (1965).",
      "journal-title": "The Computer Journal"
    }
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        "name": "EthicsHeading",
        "label": "Competing interests"
      }
    }
  ],
  "article-number": "12285"
}