DOS calculation AGAIN!

Message

dcurulla · #1 Post by **dcurulla** » Mon Aug 27, 2007 12:59 pm

Hi All,

I am sorry to bother you with DOS calculations again, but after looking at the manual and searching here in the forum, I haven't find any solution to my problem yet.

I want to run a DOS calculation of CO-Pt(111)-p(2x2), so after the geometry optimization, I add or modify the following tags to the INCAR file:

ISMEAR = -5
CHGCAR = 11
LORBIT = 11
LVTOT = .TRUE.
LELF = .TRUE.
NPAR = 1
NSW = 0

If I run the calculation with my old KPOINTS file (5x5x1), the calculation goes ok. But, I have read that I have to increase the number of KPOINTS, so I tried (10x10x2) and many others and in all cases I get the following ERROR message:

VERY BAD NEWS! internal error in subroutine IBZKPT:
Routine TETIRR needs special values for the k-mesh shifts! -3

Can somebody help me solving this problem?

Thanks

#2 Post by **admin** » Wed Aug 29, 2007 11:58 am

1) for slab calculations, use ONE k-point along z only.
2) the tetrahedron integration method needs the Gamma point to be included for a subdivision of the BZ into tertahedra, probably the even mesh did not have the Gamma point in the sample. Please try 11x11x1 or 9x9x1 or give 'Gamma' or 'gamma' in the third line of your KPOINTS file

dcurulla · #3 Post by **dcurulla** » Thu Aug 30, 2007 3:22 pm

Thanks, it works now!

Why isn't this in the manual? I think it would help a lot of people.

#4 Post by **admin** » Fri Aug 31, 2007 1:02 pm

the answer to
1) follows from general solid state textbook physics .
2) is explicitely explained in the manual, in the chapter about the KPOINTS file.

danielk · #5 Post by **danielk** » Fri Aug 31, 2007 10:22 pm

In more detail"
"Furthermore the symmetrisation of the k-mesh can lead to meshes which can not be divided into tetrahedrons (at least not by the tetrahedron division scheme implemented in VASP) -- if one uses meshes which do not have their origin at G (for certain lower symmetric types of Bravais lattices or certain non-symmetry conserving shifts). Therefore only very special shifts are allowed. If a shift is selected which can not be handled you get an error message. For reasons of safety it might be a good choice to use only meshes with their origin at G (switch 'G' or 'g' on third line or odd divisions) if the tetrahedron method is used."

dcurulla · #6 Post by **dcurulla** » Wed Sep 19, 2007 10:25 pm

Dear admin and danielk,

Thank you both for your replies.

Cheers

Dani