Re: about the optical calculations in OpenMX3.9 ( No.1 ) 
 Date: 2022/12/15 10:48
 Name: YungTing Lee
 Dear Prof. Jian Zhou,
Based on the KuboGreenwood formula, we implemented the frequencydependent optical conductivity in OpenMX3.9. The equation of frequencydependent optical conductivity can be found in (1) Phys. Rev. B 98, 115115 (2018) and (2) Phys. Rev. B 102, 075143 (2020). Both of intraband and interband transitions are included in the equation of frequencydependent optical conductivity. The way that I dealt with intraband transitions was written in section A. Optical Conductivity in the computational method in Phys. Rev. B 102, 075143 (2020).
For Q1: The Drude term (e.g. Eqs. 3 and 4 in PRB 79, 125117 (2009)) is not included in OpenMX3.9. Therefore, there is no Gamma parameter.
The smearing parameter (or lifetime) in the KuboGreenwood formula is eta (one parameter) in Eq. 1 in Phys. Rev. B 98, 115115 (2018).
For Q2: It is possible to set two different smearing parameters by using conditional expressions in the optical code. One is for intraband transitions and the other is for interband transitions. Of course, one needs to modify the optical code slightly for this purpose.
On the other hand, L. Calderin et al. have developed and implemented the KuboGreenwood formula for projectoraugmented wave datasets for Quantum Espresso and published their excellent research work in Computer Physics Communications 221, 118142 (2017). The paper is also a great reference for understanding the KuboGreenwood formula, intraband/interband transitions, and Drude components in section 2.2.
Best regards, YungTing Lee

Re: about the optical calculations in OpenMX3.9 ( No.2 ) 
 Date: 2022/12/16 10:55
 Name: Jian Zhou <zhoujian@nju.edu.cn>
 Dear Dr. Lee,
Thank you for your reply. I will read these papers carefully.
Best wishes,
Jian Zhou

