[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 2010-07-07 17:06:39:
2、如何使某一个轴不变，使另外两个轴成比例增大从而保证体积增大；
3、如何确定你做的优化是不是最优的结构。
[ Last edited by gleerat on 2010-7-8 at ...

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.