KPOINTS file: Gamma and odd Monkhorst-Pack are same?

[lahaye]

Hi

I just want to double check whether I understand this discussion
in the VASP Guide about the KPOINTS file.

A so-called Gamma centered grid using keyword 'Gamma' is
equivalent to using a Monkhorst-Pack with odd numbers ?

Or, to be explicit, are following two examples equivalent:

Code: Select all

Gamma
4 4 4
0 0 0

and

Code: Select all

Monkhorst-Pack
5 5 5
0 0 0

If I'm wrong here, can then someone explain the difference?

Thank you,
Rob.

[admin]

no, the meshes are not equivalent in general: In the Monkhurst-Pack scheme, EVEN meshes are shifted away from the origin, whereas they are not for Gamma.
Therefore, Gamma 5 5 5 (NOT 4 4 4!) is equivalent to Monkhurst-Pack 5 5 5,
but Gamma 4 4 4 gives a completely different mesh than Monkhurst-Pack 4 4 4, even for the most simple cubic case.

[yongwang2000]

Thanks.
So for KPOINT meshs with ODD numbers, Gamma is equivalent to Monkhorst, that is something I have wanted to confirm for a long time.
I think the VASP WIKI can make it clearer about this.

[martin.schlipf]

Thank you for the suggestion, I have modified wiki/wiki/index.php/KPOINTS#Monkhorst-Pack slightly to mention odd subdivisions.