# About the calculation method of the temperature rise of the system by the oscillating electric field

GROMACS version: 2021.1
GROMACS modification: No

Hi professionals,

I tried to simulate microwave heating of the system by applying oscillating electric field according to procedure shown in link below (Electric fields — GROMACS 2021 documentation). I was able to confirm the heating of the system, but I did not know how to calculate the temperature rise (ref.146 also did not show the calculation method).

It seems that the electric field energy that did not contribute to the rotation of the molecule is dissipated as heat. Does anyone know how GROMACS calculates the heat dissipation?

Best regards,
Sakemi

I don’t know if I understand your question. If you are not using a thermostat then you can directly observe the change in temperature and kinetic energy (heat). If you are using a thermostat, you need to compute how much energy the thermostat absorbed, which you can get from the difference from the reference temperature and the coupling time, in case of Berendsen or Bussi.

Dear hess,

Thank you for your reply and I apologize for my unclear question.

I would like to understand with mathematical formulas how AC electric field energy is converted to heat in GROMACS.
Also, in my simulation, I didn’t use a heat bath when applying an AC electric field.

Best regards,
Sakemi

There are no mathematical formulas on how the electric field is converted to heat. The field performs work on the system. Performing work usually leads to an increase in energy of the system. If the work per unit of time is small, the equipartitioning theorem tells up that half of this work goes into an increase in potential energy and half into increase in kinetic energy.