Is there an option to calculate circular dichroism (CD spectra) and anisotropic Dissymmetry factor in VASP.
I need to calculate the spectra for chiral system
5
-
1$\begingroup$ Is this for a solid or periodic system? My understanding is that circular dichroism (and optical rotation) is generally not implemented for periodic systems. OR was very recently implemented in CRYSTAL, so it may not be too long before CD is available as well. $\endgroup$– Tyberius ♦Commented Feb 16, 2022 at 16:01
-
$\begingroup$ I need it for periodic system $\endgroup$– 샤다ㅏCommented Feb 16, 2022 at 23:24
-
$\begingroup$ Hi, have you find a definite answer? Is it possible to calculate CD spectra using VASP? $\endgroup$– Shahid SattarCommented Aug 16, 2022 at 13:07
-
$\begingroup$ Hi @ShahidSattar I guess you're wondering the same thing as the author of this question? If you want an answer to this question faster you could consider putting a bounty on it! Just click "Start a bounty" below this comment section :) $\endgroup$– Nike Dattani - No Free TimeCommented Sep 2, 2022 at 21:55
-
$\begingroup$ This question is now on this list. $\endgroup$– Nike Dattani - No Free TimeCommented Sep 6, 2022 at 20:01
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
Its a bit tough to prove a negative, but currently I believe this isn't possible with VASP or any other QM package. Searching the VASP Wiki returns no hits for "circular dichroism" or "optical rotation" (a close cousin of CD, which requires a lot of the same machinery to compute).
In fact, optical rotation, which is arguably somewhat easier to implement than CD, was not available for periodic systems until very recently, when it was implemented in CRYSTAL. My thesis was actually focused (in part) on developing OR methods for periodic systems and as part of that I also did an extensive lit search for existing OR/CD implementations with Periodic Boundary Conditions (PBC). My search didn't yield anything and it seems CD simply hasn't been implemented for periodic systems yet.
answered Sep 12, 2022 at 19:58
$\begingroup$
$\endgroup$
The difficulty lies in the fact that the magnetic dipole $\mathbf{M}$ and electric quadrupole $\mathbf{Q}$ operators are ill-defined for periodic systems due to the unbound position operator $\mathbf{r}$. However, with a sum over states formulation, the matrix elements of $\mathbf{M}$ and $\mathbf{Q}$ can be calculated now. The VASP implementation of the OR and CD calculations have appeared within the independent particle approximation.
