From NWChem
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| 4:12:00 AM PST - Fri, Dec 6th 2013 |
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Dear all,
I have a question about using solvent implicit models for TDDFT calculations.
If the non-equilibrium PCM/TDDFT implemented in NWchem?
Thanks in advance for any comment or suggestion.
Yavar
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| Computational and Theoretical Physics Group, AEOI, Tehran, Iran
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Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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| 11:42:28 AM PST - Wed, Jan 8th 2014 |
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Hi Yavar,
We have the COSMO model in NWChem. The COSMO potential is included in the TDDFT calculation but we don’t include the reaction of the excited-state density of the molecule on the solvent or the fast response (or the non-equilibrium response). The calculation is only done with the slow component. Including the fast or non-equilibrium component (which corresponds to eps_inf ~2.0 for most solvents) is like doing a calculation in a non-polar solvent (epsilon_static ~2.0). Since non-polar solvents don’t affect the excitation energies much, it’s not a bad approximation to neglect it. The other argument to neglect it is the time scale. The electronic excitations are too fast for total solvent rearrangement to occur.
We do have the non-equilibrium response in our implementation plans but I am not sure if we will have it ready by the next release.
Best,
-Niri
niri.govind@pnl.gov
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| 3:03:39 AM PST - Fri, Jan 17th 2014 |
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Thanks
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Dear Professor Govind,
Thanks for your complete answer and consideration,
I want to calculate vertical excitation of some organic molecules in ethanol in LR-TDDFT framework
(not in RT-TDDFT), and If I understand using a COSMO with epsilon=eps_inf is in good agreement with
non-eq TDDFT?
BESTS.
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