Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants

Khanna, V. and Anwar, J. and Frenkel, D. and Doherty, M.F. and Peters, B. (2021) Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants. Journal of Chemical Physics, 154 (16). ISSN 0021-9606

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Abstract

Free energies of crystals computed using a center of mass constraint require a finite-size correction, as shown in previous work by Polson et al. [J. Chem. Phys. 112, 5339-5342 (2000)]. Their reference system is an Einstein crystal with equal spring constants. In this paper, we extend the work of Polson et al. [J. Chem. Phys. 112, 5339-5342 (2000)] to the case of differing spring constants. The generalization is convenient for constraining the center of mass in crystals with atoms of differing masses, and it helps to optimize the free energy calculations. To test the theory, we compare the free energies of LiI and NaCl crystals from calculations with differing spring constants to those computed using equal spring constants. Using these center of mass finite size corrections, we compute the true free energies of these crystals for different system sizes to eliminate the intrinsic finite-size effects. These calculations help demonstrate the size of these finite-size corrections relative to other contributions to the absolute free energy of the crystals.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Chemical Physics
Additional Information:
Copyright 2021 American Institute of Physics. The following article appeared in The Journal of Chemical Physics 154, 2021 and may be found at http://dx.doi.org/10.1063/5.0044833 This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
ID Code:
154942
Deposited By:
Deposited On:
17 May 2021 09:25
Refereed?:
Yes
Published?:
Published
Last Modified:
16 Jun 2021 09:14