Simple question... What is the definition of "c" regarding the Berry-Phase term R.BP
R.BP = ( 0.00000, 0.00000, 1.63007 ) electrons Angst
+( 0.00000, 0.00000, 4.00100 ) *c
Most examples depict R.BP as a 1x3 matrix. I don't know how to treat the second term. What is the function of "c" ? Thanks in advance for your reply.
在自旋极化计算的时候！

自旋极化计算的时候

一看到有人回复，高兴了一下，后来发现是。。。。。
我当然知道是自旋极化的时候，没有自旋时不会出现那一项，我问的是那个“c”怎么处理，前面还有一个加号。
有人回复：this line is the lattice vector AIGPAR multiplied with the spin multiplicity of the bands. Please check it to remove possible unphysical contributions to the Berry phase terms caused by the periodic boundary conditions.
还有人说：What does an 'unphysical contribution to the berry phase term' look like, in this line?
还有人说：it would be an integer multiple of the second line ( )*c included in ,.
可是我还是没看懂！
来自：http://cms.mpi.univie.ac.at/vasp-forum/forum_viewtopic.php?4.4460