VASP 自洽与非自洽计算

非自洽计算仍有电子步的迭代

在进行非自洽计算时（ISTART = 1, ICHARG =11），电子步仍然会做迭代计算（至少在NELMIN内）.  一个原因是改变了k-points and/or number of bands，ISTART将reset为0，即读入的波函数（轨道）并未使用，需要在新的参数下重新收敛波函数，但保持电荷密不变（在VASP计算电子机台算法中，There is one outer loop in which the charge density is optimized, and one inner loop in which the wavefunctions are optimized.）

以下是VASP论坛中，关于WAVECAR读取的回答

The old WAVEFUN can ONLY be used if the setup of the calculation which wrote the file is exactly the same as the setup of the calculation which continues : same
cell dimensions,
PREC,
k-points,
continue from CONTCAR as the new start geometry,... .
If you change ANY of these parameters (like the k-meshes,...) please continue from CHGCAR.

In WAVECAR, only the coefficients of the wavefunctions are stored, not the wavefucntions themselves. Therefore really EVERYTHING has to be compatible in order that the information read from WAVECAR makes sense.

vaspwiki关于波函数（轨道）和电荷密度的说明：

independent quantitiesInput charge density and wavefunctions are independent quantities (at start-up these quantities are set according to INIWAV and ICHARG).

Within each selfconsistency loop, the charge density is used to set up the Hamiltonian, then the wavefunctions are optimized iteratively so that they get closer to the exact wavefunctions of this Hamiltonian.

From the optimized wavefunctions, a new charge density is calculated, which is then mixed with the old input-charge density.