# [Wannier] momentum operator matrix

Yu Zhang zhyhku at gmail.com
Tue Mar 10 22:04:48 CET 2015

```Dear wannier90 users and developers,

I want to get the the matrix element of momentum operator, i.e., <Rn|
\nabla |0m>. I didn't find any instructions to get the matrix element from
wannier90. Does anybody know how to get the momentum operator matrix?