IDIPOL=1/2/3

IDIPOL也可以等于4

For IDIPOL=1-3, the dipole moment will be calculated only parallel to the direction of the first, second or third lattice vector, respectively. The corrections for the total energy are calculated as the energy difference between a monopole/dipole and quadrupole in the current supercell and the same dipole placed in a super cell with the corresponding lattice vector approaching infinity. This flag should be used for slab calculations.

For IDIPOL=4 the full dipole moment in all directions will be calculated, and the corrections to the total energy are calculated as the energy difference between a monopole/dipole/quadrupole in the current supercell and the same monopole/dipole/quadrupole placed in a vacuum, use this flag for calculations for isolated molecules.

一开始电场不要加的太大，电场的强度逐渐加上去。比如一开始做一个电场强度很小的计算，得到了收敛的电荷密度和波函数之后，再增加电场强度，读入上一步的电荷和波函数进行计算。。。。。这样的方式逐渐增加电场强度。

ISTART = 1