Gmx dos Quantum Corrected Heat Capacity

[plee1237]

GROMACS version: 2019.4
GROMACS modification: Yes/No with Plumed

Hi,

I’m trying to calculate the heat capacity of my system. After running a 100-ps NVT simulation with frequently saved trajectory I tried to use gmx dos to calculate the quantum corrected heat capacity. My question is that in the dos.log file it gives the value of heat capacity, does this heat capacity refer to the already corrected heat capacity or just the correction? I’m asking this because I have also calculated the classical heat capacity and it is twice larger than the value given by dos. If the dos value is the final heat capacity then it means that the correction is negative, which does not seem right. I understand that I’m using two different trajectories with much different time step values and the fluctuations could change a lot, but the difference between dos value and the classical value is still larger than I expected. Any comment and suggestion is welcomed! Thank you so much in advance!

Regards,
Peiyin

[alevilla]

Hi,

@plee1237

GROMACS version: 2019.4
GROMACS modification: Yes/No with Plumed

Hi,

I’m trying to calculate the heat capacity of my system. After running a 100-ps NVT simulation with frequently saved trajectory I tried to use gmx dos to calculate the quantum corrected heat capacity. My question is that in the dos.log file it gives the value of heat capacity, does this heat capacity refer to the already corrected heat capacity or just the correction?

the log file reports the heat of capacity (not just the correction) as far as I can see from the source code

I’m asking this because I have also calculated the classical heat capacity and it is twice larger than the value given by dos.
If the dos value is the final heat capacity then it means that the correction is negative, which does not seem right. I understand that I’m using two different trajectories with much different time step values and the fluctuations could change a lot, but the difference between dos value and the classical value is still larger than I expected. Any comment and suggestion is welcomed! Thank you so much in advance!

I am sorry I am not an expert in those analysis. Just know that the approach has been used (among other papers) in the following paper https://pubs.acs.org/doi/10.1021/ct200731v

Regards,
Peiyin

Best regards
Alessandra

[Bright]

Hi,

Maybe, the correction of the quantum is negative, if you want to know a simple model as Einstein Model, which use the phonon to correcte the C, you will get it.
However, I don’t understand the meaning of this scentence, I’m using two different trajectories with much different time step values and the fluctuations could change a lot, but the difference between dos value and the classical value is still larger than I expected.

Best,
Yuhao He