[Q-e-developers] About "molteplicities" in the resp_mat.f90 script

[Paolo Giannozzi]

On Tue, 2014-04-22 at 23:07 +0800, huangxu1706 at sina.com wrote:

> I'm confused about the part of "molteplicities" in the resp_mat.f90 script 

I do not see such "script" (or more likely, fortrano file) anywhere in
the QE distribution

Paolo

> which is used to calculate U value of metal oxides. This part is after the 
> construction of the first matrix = chi0m1 - chim1, and is important for the 
> U-extrapolation from primitive cell to supercell. But I'm not sure the basic 
> idea of this part, because it is beyond the theoretical introduction of the 
> linear response (M. Cococcioni and S. de Gironcoli, Phys. Rev. B 71, 035105 
> (2005)). 
> 
> For this part, I checked the output Umat.n.n.n.out files and found that the 
> variables in the loops, i00, d0, mol, kp, kp0 and spinp, must have something 
> to do with the "number of shells, shell #n: pc, sc, spinp dist chi_pc and 
> chi_sc" in the output. But what is the physical meaning of those variables? 
> How are they correlated with the chi0 and chi in primitive cell, and those 
> in super cell? Why is the "molteplicities" necessary?
> 
> I'm working on a project about adapting the U-calculation which was designed 
> for 3-D bulk system ny QE to 2-D surface system. I've made a lot of changes 
> in the resp_mat.f90 script. I got reasonable U values in the first matrix = 
> chi0m1 - chim1, but when it reached the molteplicities part, the calculated 
> U values are strange. I believe that this part is also for 3-D system that 
> some variables or loops also need to be modified for 2-D system. I can't treat 
> it as a "black box" and trust its output. So I have to understand how this part 
> works.
> 
> Thank you,
> Xu Huang
> 
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222