Our group recently developed an accurate and easily extendable method to deal with lattice dynamics of solids, the Temperature Dependent Effective Potential (TDEP) [1, 2]. TDEP is based on ab initio molecular dynamics simulations (MD) and allows to build the best possible harmonic potential energy surface at finite temperature. With help of TDEP we can presetup supercells for MD in such a way that it will drastically reduce the amount of necessary calculations and computer time used. The effect is illustrated on hcp Fe as a at extreme earth-core conditions as a model system and its thermal equation of state as a model problem. This work explains the technical details behind the method.
This work was supported by Grant of Russian Federation Ministry for Science and Education (grant No. 14.Y26.31.0005).
References
[1] O. Hellman, I. A. Abrikosov, and S. I. Simak, “Lattice dynamics of anharmonic solids from first-principles”, Phys. Rev. B 84(2011), 180301(R).
[2] O. Hellman, P. Steneteg, I. A. Abrikosov, and S. I. Simak “Temperature dependent effective potential method for accurate free energy calculations of solids”, Phys. Rev. B 87, 104111 (2013)