# [Wannier] hamiltonian matrix in wannier

Liping Chen liping.chen at rochester.edu
Fri Jan 17 16:40:52 CET 2014

```Dear all,

Sorry for the spam. When I checked the mailing list archive in the homepage of wannier90, I found the email I sent out with only one sentence. I also received one copy, but it's normal as below.

Is there anyone who can help with the following questions about hamiltonian matrix in wannier90? Since the dimension of position matrix is AA_R(num_wann,num_wann,num_kpts,3) and the dimension of hamiltonian matrix is ham_r(num_wann,num_wann,nrpts), I don't know what's the difference between num_kpts and nrpts. Thanks!

Best,

Liping

----- Original Message -----
From: "Liping Chen" <liping.chen at rochester.edu>
To: wannier at quantum-espresso.org
Sent: Thursday, January 16, 2014 2:44:29 PM
Subject: hamiltonian matrix in wannier

Dear wannier users,

>From the manual, I can get hamiltonian in the WF basis by setting HR_PLOT = true. Below are the codes to write the hamiltonian matrix in hamiltonian.F90
###################################################################
write(file_unit,*) header ! Date and time
write(file_unit,*) num_wann
write(file_unit,*) nrpts
write(file_unit,'(15I5)') (ndegen(i),i=1,nrpts)
do irpt=1,nrpts
do i=1,num_wann
do j=1,num_wann
write(file_unit,'(5I5,2F12.6)') irvec(:,irpt), j, i,&
ham_r(j,i,irpt)
end do
end do
end do
###################################################################
What's the relationship between num_kpts and nrpts? The former should be the total number of the kpoints, right? It seems that there are degeneracies for nrpts. Does it mean that the sum(ndegen(i),i=1,nrpts) = num_kpts? The hamiltonian matrix elements with the same degeneracy are the same? What is irvec(:,irpt) for?

Thanks,

Liping Chen
Department of Chemistry
University of Rochester

```

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