Accurate path-integral molecular dynamics calculation of aluminum with improved empirical ionic potentials

ZX Yan and CY Zhang and X Liu and Q Miao and M Fang and W Kang, PHYSICAL REVIEW B, 106, 174107 (2022).

DOI: 10.1103/PhysRevB.106.174107

We show that an accurate description of the interplay between the anharmonic ionic interaction and the zero -point fluctuation of ions in crystalline aluminum (Al) can be achieved using the path-integral molecular dynamics (PIMD) method in conjunction with improved empirical modified embedded-atom method (MEAM) potentials. Our results show that the zero-point fluctuation of ions is noticeable at a temperature between 200 K and 250 K, roughly half of the Al Debye temperature of 428 K, with a selective influence on mechanical properties. The effect provides appreciable corrections to the lattice constant a, bulk modulus B, and elastic constant C11 at low temperature, but without much influence on elastic constants C12 and C44. With a revised MEAM potential which takes into consideration the influence of zero-point fluctuations, the PIMD method has a much improved accuracy in a, B, and the C's up to 700 K, when compared with precision experimental measurements. The largest errors of a and B can even be reduced by about an order in percentage below 300 K.

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