1. Ab initio screening for materials with negative thermal expansion Zimin T.M., Lysogorskiy Y.V. Institute of Physics, Kazan Federal University, 18 Kremlevskaya st., Kazan, Russia, 420008

2. Relevance Nanoscale electronics Mechanical engineering Creation and exploitation of high-precision optical equipment Creation and exploitation of thermoelectric devices Creation and exploitation of fuel cells new generation Negative thermal expansion (NTE) ─ decrease of the linear dimensions and volume upon heating under constant pressure. Over the past two decades, the field of negative and zero thermal expansion has rapidly expanded, because the materials with such properties have a huge range of applications. In general, such materials are necessary to many industries with a wide range of operating temperatures. 2 1) Lind, C. (2012). Two decades of negative thermal expansion research: where do we stand?. Materials, 5(6), 1125-1154. [1]

3. Mechanisms of NTE 3 Magnetovolume effect [1, 2] Atomic radius contraction [1] RUMs («Rigid Unit Modes») [1] 1)Takenaka, K. (2012). Negative thermal expansion materials: technological key for control of thermal expansion. Science and Technology of Advanced Materials, 13(1), 013001. 2)Takahashi, Y., & Nakano, H. (2006). Magnetovolume effect of itinerant electron ferromagnets. Journal of Physics: Condensed Matter, 18(2), 521.

4. FIG. 2. (a) Structure of ScF3. (b) Geometry modification of bonds Sc – F upon heating [3] 3) Li, C. W., Tang, X., Munoz, J. A., Keith, J. B., Tracy, S. J., Abernathy, D. L., & Fultz, B. (2011). Structural relationship between negative thermal expansion and quartic anharmonicity of cubic ScF 3. Physical review letters, 107(19), 195504. FIG. 3. Quadratic (harmonic) and quartic (anharmonic) fits for phonon potential 4

5. Research objects 5 Соединение AgZnF 3 Mg 3 NF 3 KMgF 3 CsMgF 3 LiBaF 3 RbPbF 3 RbMnF 3 RbYbF 3 RbFeF 3 MoF 3 Соединение TaF 3 NaVF 3 NbF 3 RbHgF 3 CsCdF 3 CsCaF 3 RbVF 3 KPdF 3 RbCaF 3 Space group symmetry Pm3m

6. Computer simulation methods. Density functional theory (DFT) 6 [4] MedeA® and Materials Design®, 2013, www.materialsdesign.com.www.materialsdesign.com [5] Kresse, G. "Software VASP, Vienna, 1999; G. Kresse, J. Furthmüller." Phys. Rev. B 54.11 (1996). DFT exchange-correlation: GGA – PBE Planewave сut off: 400 eV K – mesh in Brillouin zone: 5x5x5 Convergence: 0.005 eV/Ang [4][4][5][5]

7. Thermal expansion coefficient method of evaluation 7 (1) (3) (2) (4)

8. Thermal expansion coefficient method of evaluation 88

9. 9 Compound -0.13-1,6─ -0.37-3,2─ -1.92-8.3-7.8 [3] Temperature dependence coefficient of linear thermal expansion 3) Li, C. W., Tang, X., Munoz, J. A., Keith, J. B., Tracy, S. J., Abernathy, D. L., & Fultz, B. (2011). Structural relationship between negative thermal expansion and quartic anharmonicity of cubic ScF 3. Physical review letters, 107(19), 195504.

10. Conclusion 10

11. Thank you for attention! 11