[Wien] Unexpected value of the plasma frequency for Gold with GGA+SOC!!!

[Osama Yassin]

Dear Prof. Blaha and colleagues,,,


I 'm trying to reproducing the dielectric function of Gold as reported by Kathrin Glantschnig1,2,3 and Claudia Ambrosch-Drax in:


http://iopscience.iop.org/article/10.1088/1367-2630/12/10/103048/meta

and from which I quote:

"Relativistic effects also influence the plasma frequency changing from 9.44 to 8.96 eV when taking scalar-relativistic terms into account. The inclusion of SO interaction leads to an additional decrease to 8.81 eV. It now agrees well with a value of 8.83 eV extracted from experimental data by Cooper et al [18<http://iopscience.iop.org/article/10.1088/1367-2630/12/10/103048/meta#nj349811bib18>]."

1- I use Wien2k 16.1 (after fixing the bug related to lapw2 in the DFT+U calculations) to calculate the optical constants of bulk Gold.
2- I followed the user guide (i.e. increasing the maximum energy and setting Rkmax to a higher value ~11). and got the expected value of Wp when using using GGA alone.
2- Upon inclusion of the spin-orbit coupling I got a value ~ 12.6 eV!!!. The inclusion of SOC is expected to reduce the value of Wp but here the opposite happened.
3- By switching off the SOC and I again got the expected value of Wp when GGA alone is used.

My question:

1- Why Wp increases when SOC is included in the optical calculations?. What is wrong

- the lattice parameter I used is 4.1011 Angstrom.
- a dense mesh of 41x41x41 i used for the optical calculations..


O A Yassin








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