cpmd

CPMD方法Car-Parrinello Molecular Dynamics（简称CPMD）是一种第一原理分子动力学（ab initio molecular dynamics）方法，该方法利用了赝势、平面波基矢和密度泛函理论（DFT）对原子（分子）间作用力进行计算，

In contrast to Born–Oppenheimer molecular dynamicswherein the nuclear (ions) degree of freedom are propagated using ionicforces which are calculated at each iteration by approximately solvingthe electronic problem with conventional matrix diagonalizationmethods, the Car–Parrinello method explicitly introduces the electronicdegrees of freedom as (fictitious) dynamical variables, writing anextended Lagrangian for the system which leads to a system of coupled equations of motionfor both ions and electrons. In this way an explicit electronicminimization at each time step, as done in Born-Oppenheimer MD, is notneeded: after an initial standard electronic minimization, thefictitious dynamics of the electrons keeps them on the electronic ground statecorresponding to each new ionic configuration visited along thedynamics, thus yielding accurate ionic forces. In order to maintainthis adiabaticity condition,it is necessary that the fictitious mass of the electrons is chosensmall enough to avoid a significant energy transfer from the ionic tothe electronic degrees of freedom. This small fictitious mass in turnrequires that the equations of motion are integrated using a smallertime step than the one (1–10 fs) commonly used in Born–Oppenheimermolecular dynamics.

CPMD程序