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xirainbow

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[交流] 【分享】Different types of PP can be mixed

Different types of PP can mix together in one calculation.

http://www.democritos.it/pipermail/pw_forum/2010-June/017345.html
     The big advantage of ultrasoft PPs is to require a much smaller cutoff. In the case of Fe-Te-Se systems, Fe is by far the hardest element. The cutoff needed for ultrasoft Fe might well be sufficient for norm-conserving Te (and Se as well).
     The reason why USPP have been introduced is not for some form of masochism(受虐狂), but because for certain elements of the first row (C-N-O-F)(第一次出现p轨道) or for first row transition metals(第一次出现d轨道) or rare earths(scandium_21, yttrium_39, and the fifteen lanthanides_57~71,)NCPP would require very high cutoff. Most other elements (including Se,Te) can be treated with much lower cutoffs and do not need USPP construction...
          It is convenient therefore to use USPP for the hard elements while you can stick to NCPP when this is not needed. And you CAN mix different types.

http://blog.sina.com.cn/s/blog_5f15ead20100j51b.html

[ Last edited by xirainbow on 2010-6-21 at 20:20 ]
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