Temperature and its control in molecular dynamics simulations

ABSTRACT

The earliest molecular dynamics simulations relied on solving the Newtonian or equivalently the Hamiltonian equations of motion for a system. While pedagogically very important as the total energy is preserved in these simulations, they lack any relationship with real-life experiments, as most of these tests are performed in a constant temperature environment that allows energy exchanges. So, within the framework of molecular dynamics, the Newtonian evolution equations need to be modified to enable energy exchange between the system and the surroundings. The prime motive behind allowing energy exchange is to control the temperature of the system. Depending on the temperature being controlled and the modifications made to the equations of motion, different evolution equations, or thermostat algorithms, can be obtained. This work reviews the recent developments in controlling temperature through deterministic algorithms. We highlight the physical basis behind the algorithms, their advantages, and disadvantages, along with the situations where they are applicable. The review ends with a brief discussion on open-ended questions related to thermostatted dynamics.

KEYWORDS:

• Temperature
• thermostats
• molecular dynamics
• ergodicity

Acknowledgments

PKP acknowledges the support for this research provided in part by the Department of Science and Technology, Govt. of India, under the scheme DST-ECR.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Department of Science and Technology, Govt. of India [DST-ECRA, grant number ECR/2018/000340].