[CP2K-user] [CP2K:19103] Re: No agreement between the LR and RT absorption spectra
belizsertcan at gmail.com
Mon Jul 10 14:43:45 UTC 2023
Regarding the mismatch between CP2K and Gaussian TDDFT results, once should
use the TDA keyword in Gaussian instead of TD to get an exact match as CP2K
employs the Tamm-Dancoff approximation. Furthermore, I would highly
recommend turning on the Poisson section and setting the solver to MT
instead of analytical.
Since you are working with a heavy element I would also consider using a
bigger basis such as TZVP maybe even TZV2P. With these additions I think
you will be able to match the RTP spectrum better, but I would not expect a
perfect match. In my opinion what you have with the positions of the sticks
is not so bad.
On Monday, 10 July 2023 at 10:55:39 UTC+2 Natalia K wrote:
I am calculating the absorption spectra for a silver chain using both
linear response (TDDFPT) and real-time propagation implemented in CP2K 9.1.
Within the RT propagation, I apply a delta kick in all three directions and
then take the Fourier transform of the dipole moment and get the average
(over three directions) spectrum that is in a very good agreement with the
literature. In particular, with another GGA linear-response calculation
with the Gaussian code (image attached, top - my results, bottom -
reference). Within the TDDFPT approach, I calculate the oscillator strength
which should give the same frequencies as the real-time approach, but it
doesn't. In the figure attached, the oscillator strength is plotted with
impulses. I tested many different parameters but LR never agrees with RT. I
also tested a simpler system, a water molecule, and got a better agreement
between the two methods, but still not as perfect as here, for instance:
I would appreciate any help or suggestion. I attach both RT and LR input
files used to obtain the results on the figure.
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