Modified velocity scaling scheme for molecular dynamics at constant temperature and/or pressure

A modified and generalized velocity scaling (VS) scheme to integrate equations of motion (EOM) for constant temperature and/or pressure molecular dynamics (MD) simulations in the framework of the leapfrog algorithm is presented. This modified VS scheme (MVS) enables us to integrate EOM with a velocity dependent force such as a friction term easily maintaining the accuracy of the leapfrog (Verlet) algorithm. The scaling factor in the MVS does not depend on the detailed expression of the friction term. Therefore, it can be incorporated in various constant temperature and/or pressure methods. The accuracy of integrations in the MVS and original VS was compared in a Lennard-Jones fluid. It is confirmed that the MVS holds the Verlet's accuracy, while original VS fails.