[gmx-users] Heat capacity Cv

Alexander Alexander alexanderwien2k at gmail.com
Wed Apr 20 11:06:52 CEST 2016

Dear Gromacs user,

In order to get heat capacity for a solid, I do a long and well converged
mini-NPT-NVT simulations and then invoke below command to get Cv;

gmx energy -f nvt.edr -nmol 8192 -fluct_props -driftcorr -b 500 -o cv.xvg

However, Cv comes always to "24.5815 J/mol K" for different temperature (20
K, 50, 100 K ... 298.15 K ...).

Cv=24.5815 J/mol K is quite reasonable for T=298.15 K and higher
temperature agreeing well with DuLong–Petit law and my quantum
calculations, but I expected to see decreasing in Cv for lower temperature
based on the same rules.

Quantum correction also does not help as it is a plus.

So, any idea would be greatly appreciated.


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