[Pw_forum] grid shift

[Fan Yang]

Dear everyone:

I have some questions about grid offsets.

In our input file, the k-points are automatically generated with uniform grid, and the grid offsets are either set as 0 (no offset) or 1 (grid displaced by 1/2 step). But the problem is that we got different results with different offsets.

For example, we tested the adsorption of one oxygen atom on three low-index Pt crystal planes, namely, Pt(100), Pt(110) and Pt(111). With grid shift (0 0 0), the adsorption energy of O on Pt(110) is slightly larger than on Pt(100), but much larger than on Pt(111). However, with grid shift (1 1 1), the order of adsorption energy is Pt(110)>Pt(111)>Pt(100). 

Which result is more reasonable?

Best Regards & Merry Christmas,

Fan Yang
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Fan Yang
PH.D Candidate in Electrochemistry
College of Chemistry and Molecular Science
Wuhan University, 430072, Hubei Province, China
E-mail:shrek_826 at yahoo.com.cn
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