MOMENTUM CONSERVATION LAW IN THE CAR-PARRINELLO METHOD
MOMENTUM CONSERVATION LAW IN THE CAR-PARRINELLO METHOD
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DOI：
10.1103/physrevb.59.15126
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发表时间：
1999-06
影响因子：
3.7
通讯作者：
T. Morishita;S. Nosé
中科院分区：
文献类型：
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作者：
T. Morishita;S. Nosé
研究了Car-Parrinello（CP）方法中的动量守恒律。在经典分子动力学（MD）中，当拉格朗日量不受均匀空间位移的影响时，离子总动量是守恒量。在没有恒温器和压力活塞的情况下，离子总动量不再是守恒量。但以与经典MD相同的方式，可以导出另一个守恒量，它是总离子动量的和，对应于电子波函数。在这种情况下，总离子动量的不守恒不会产生严重的问题。然而，当在恒温CP情况下引入多个恒温器时，对应于动量的守恒量不存在。在某些情况下，离子总动量的涨落会被放大，特别是在金属态。我们分析了这个问题，并得出结论，在这种类型的模拟中，有必要增加总离子动量的重置程序。
Momentum conservation law in the Car-Parrinello (CP) method is investigated. In classical molecular dynamics (MD), a total ionic momentum is a conserved quantity when a Lagrangian is invariant by a uniform spatial displacement. The total ionic momentum is no longer a conserved quantity in the original CP case, in which no thermostat and no pressure piston are considered. But in the same manner as classical MD, another conserved quantity can be derived, which is a sum of the total ionic momentum and corresponds to electronic wave functions. In this situation, the nonconservation of the total ionic momentum produces no serious problem. However, when multiple thermostats are introduced in the constant-temperature CP case, a conserved quantity corresponding to momentum does not exist. The fluctuation of the total ionic momentum is amplified strongly in some situations, especially in metallic state. We have analyzed this problem and concluded that it is necessary to add the resetting procedures of the total ionic momentum in this type of simulation.