[交流] 【求助成功】VASP中，如何固定磁矩做结构优化已有6人参与

Originally posted by gleerat at 2010-07-08 16:13:50:

不清楚，我原来做的是没有固定磁矩，然后晶格变化有些大，老师就说这个很出乎意料，让我“fix Spin”。说是对比一下看看结果差别大不大。

6.35   NUPDOWN
NUPDOWN = difference between number of electrons in up and down spin component
Allows calculations for a specific spin multiplet, i.e. the the difference of the number of electrons in the up and down spin component will be kept fixed to the specified value. There is a word of caution required: If NUPDOWN is set in the INCAR file the initial moment for the charge density should be the same. Otherwise convergence can slow down. When starting from atomic charge density (ICHARG=2), VASP will try to do this automatically by setting MAGMOM to NUPDOWN/NIONS. The user can of course overwrite this default by specifying a different MAGMOM (which should still result in the correct total moment). If one starts from the wavefunctions, the initial moment will be always correct, because VASP will “push” the required number of electrons from the down to the up component. If starting from a chargedensity supplied in the CHGCAR file (ICHARG=1), the initial moment is usually incorrect!
If no value is set (or NUPDOWN=-1) a full relaxation will be performed. This is also the default.