Yambo Community Forum

Posted: **Sun Mar 13, 2022 5:37 am**

Dear Developers,

I can find three variables which relate to the dipole matrix element in the ndb.dipoles_fragment_xx, i.e. “DIP_iR_k_0001_spin_0001”, "DIP_P_k_0001_spin_0001'' and DIP_v_k_0001_spin_0001. However, I have two questions about these three variables as following:

1. I want to know that the difference between these three variables.
2. What is the unit of these three variables.

Best,
Pang

Posted: **Mon Mar 14, 2022 3:14 pm**

Dear Pang,

they are respectively the matrix element <v|ir|c>, <v|p|c> and <v|V|c>, ie the matrix elements of position, momentum and velocity.
You can see here how they are related:
/src/dipoles/DIPOLE_transverse.F

Code: Select all

266            !
267            ! DIP_iR(c,v) = i <v|r|c> = i <v|[r,H]|c>/(Ec-Ev) =
268            !             = i <v|i p|c>/(Ec-Ev) + i<v|[x,Vnl]|c>/(Ec-Ev) =
269            !             = - <v|-i grad|c>/(Ec-Ev) +i<v|[x,Vnl]|c>/(Ec-Ev) =
270            !             =   <v|-i grad|c>/(Ev-Ec) -i<v|[x,Vnl]|c>/(Ev-Ec) =
271            !             =   P_vc/(Ev-Ec) -i<v|[x,Vnl]|c>/(Ev-Ec)

The units should be respectively bohr and bohr*Hartree

Best,
Daniele

Posted: **Tue Mar 15, 2022 7:37 am**

Dear Daniele,

Thanks for your reply and help!
I got it.

Best,
Pang

Yambo Community Forum

ndb.dipoles_fragment_xx

ndb.dipoles_fragment_xx

Re: ndb.dipoles_fragment_xx

Re: ndb.dipoles_fragment_xx