## Absorption with light polarized in an arbitrary direction

Deals with issues related to computation of optical spectra, in RPA (-o c) or by solving the Bethe-Salpeter equation (-o b). Includes local field effects, excitons, etc.
luonn
Posts: 13
Joined: Mon Nov 12, 2018 4:52 pm

### Absorption with light polarized in an arbitrary direction

Dear Yambo developers and users:
I want to know if yambo can calculate the light absorbance of a 2D material when the light propagates in an arbitrary direction, i.e. neither parallel nor perpendicular to the surface of the 2D material?

We know that by adjusting the BLongDir parameter, the dielectric function, epsilon_xx (1 0 0), epsilon_yy (0 1 0), epsilon_zz ( 0 0 1), can be obtained.
% BLongDir
1.000000 | 0.000000 | 0.000000 | # [BSS] [cc] Electric Field
%
if BLongDir is set as follows:
% BLongDir
1.000000 | 0.000000 | 1.000000 | # [BSS] [cc] Electric Field
%
then the obtained result is epsilon_xx+epsilon_yy, or other epsilon that discribe the absorption with light propagates in the xz plane with an angle of pi/4 ?

Thanks a lot

Nannan Luo
Nannan Luo
Low-Dimensional Materials and Devices Laboratory,
Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University
C2-7, iPark, Nanshan district, Shenzhen, Guangdong province, China 518055
Tel: (+86)18811369291
E-mail: luo-nn@sz.tsinghua.edu.cn

Daniele Varsano
Posts: 2725
Joined: Tue Mar 17, 2009 2:23 pm
Contact:

### Re: Absorption with light polarized in an arbitrary directio

Dear Nannan Luo,
or other epsilon that discribe the absorption with light propagates in the xz plane with an angle of pi/4 ?
Yes, the BLongDir is a versor of module 1, then it is multiplicated for the small q0.

Code: Select all

``````% BLongDir
1.000000 | 0.000000 | 1.000000 | # [BSS] [cc] Electric Field
%``````
is a vector 1/sqrt(2)[1,0,1]

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
http://www.max-centre.eu/