Method to extract anharmonic force constants from first principles calculations
نویسندگان
چکیده
A method for extracting force constants FCs from first principles is introduced. In principle, provided that forces are accurate enough, it can extract harmonic as well as anharmonic FCs up to any neighbor shell. Symmetries of the FCs as well as those of the lattice are used to reduce the number of parameters to be calculated. The results are illustrated for the case of the Lennard-Jones potential, wherein forces are exact and FCs can be analytically calculated, and Si in the diamond structure. The latter are compared to the previously calculated harmonic FCs.
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