title: Sampling the isothermal-isobaric ensemble by Langevin dynamics.
abstract: We present a new method of conducting fully flexible-cell molecular dynamics simulation in isothermal-isobaric ensemble based on Langevin equations of motion. The stochastic coupling to all particle and cell degrees of freedoms is introduced in a correct way, in the sense that the stationary configurational distribution is proved to be consistent with that of the isothermal-isobaric ensemble. In order to apply the proposed method in computer simulations, a second order symmetric numerical integration scheme is developed by Trotter's splitting of the single-step propagator. Moreover, a practical guide of choosing working parameters is suggested for user specified thermo- and baro-coupling time scales. The method and software implementation are carefully validated by a numerical example.
authors.affiliation: Laboratory of Computational Physics, Huayuan Road 6, Beijing 100088, People's Republic of China.
authors.forename: Xingyu
authors.initials: X
authors.lastname: Gao
authors.affiliation: Institute of Applied Physics and Computational Mathematics, Fenghao East Road 2, Beijing 100094, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fang
authors.affiliation: Institute of Applied Physics and Computational Mathematics, Fenghao East Road 2, Beijing 100094, People's Republic of China.
authors.forename: Han
authors.initials: H
authors.lastname: Wang