Rights statement: 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.
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants
AU - Khanna, V.
AU - Anwar, J.
AU - Frenkel, D.
AU - Doherty, M.F.
AU - Peters, B.
N1 - 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.
PY - 2021/4/28
Y1 - 2021/4/28
N2 - 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.
AB - 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.
KW - Crystals
KW - Iodine compounds
KW - Lithium compounds
KW - Sodium chloride
KW - Springs (components)
KW - Center of mass
KW - Einstein crystal
KW - Finite size effect
KW - Finite-size corrections
KW - Free-energy calculations
KW - NaCl crystal
KW - Reference systems
KW - Spring constants
KW - Free energy
U2 - 10.1063/5.0044833
DO - 10.1063/5.0044833
M3 - Journal article
VL - 154
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 16
M1 - 164509
ER -