Yambo Community Forum

Dear all,

I recently calculate exciton lifetime using eq[1] and eq[2] (https://journals.aps.org/prb/pdf/10.110 ... 107.235407). However, I do not understand how to obtain the transition dipole moments $\mu$ of eq[2].
I have obtain qp energy from tutorial(https://wiki.yambo-code.eu/wiki/index.p ... rial:_h-BN) and perform following bse caculation under tutorial(https://wiki.yambo-code.eu/wiki/index.p ... step_guide).
I have obtain dipole file ndb.dipoles and read it with python yambopy. But I found that the values of ndb.dipoles obtained from Step 1: Static screening are the same as those from Step 4: Include previous quasiparticle (GW) results. It really confuses me. Is this dipole the $\mu$ eq[2] I want？
So I digged out <G|p|S>=\sum_{vck} A_{vck} <vk|p|ck>eq[9](https://journals.aps.org/prl/pdf/10.110 ... .95.247402) and have two questions:
1.Does file ndb.dipoles store <vk|p|ck> instead of <G|p|S> or $\mu$ I want？
2.If question 1 is TRUE, could you please tell me how to obtain the coefficient A_{vck} and finally get $\mu$ to calculate exciton lifetimes?


Thanks in advance
Tang
PhD student from Beijing Normal University

Dear Tang,

1.Does file ndb.dipoles store <vk|p|ck> instead of <G|p|S> or $\mu$ I want？

Yes the ndb.dipoles database contains <vk|p|ck>

2.If question 1 is TRUE, could you please tell me how to obtain the coefficient A_{vck} and finally get $\mu$ to calculate exciton lifetimes?

A_{vck} are the BSE eigenvector and they are stored in the ndb.BS_diago database, you can also read them using yambo-py.

Best,

Daniele

Dear Dr. Daniele Varsano,
​
Thank you very much for taking the time to respond to my question. Your insights have been incredibly valuable and have provided me with enormous inspiration to tackle the issue at hand.​ And I just found (https://wiki.yambo-code.eu/wiki/index.p ... _structure) which might help me obtain the A_{cvk} I need.

Best regards
Tang

Dear Daniele,

thanks again for your professional guidance

I try to calculate the <G|p|S> now, but I do not know the units of A_{vck} and <vk|p|ck> from ndb.dipoles database. could you please tell me where can I find the units system that Yambo use in ndb.dipoles database?

Best
Tang
BNU