From NWChem
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| 6:35:19 PM PST - Sat, Feb 21st 2015 |
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I recently made some updates and improvements to the nw_spectrum.py script included with NWChem, as documented in this thread. One of its capabilities is supposed to be plotting DFT vspec virtual spectrum output. I can't find any documentation about vspec, or any input files demonstrating its use. I do do see source code apparently implementing the functionality. I presume that somebody at some time -- perhaps Kenneth Lopata, author of nw_spectrum.py -- has used this feature, hence a parser for it in nw_spectrum.py.
Is this feature undocumented and untested because it's unfinished? I would try to come up with a vspec demonstration input file for use with nw_spectrum.py by working backward from the source code, but I don't want to put in the effort if the feature is not actually working.
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| 6:38:02 AM PDT - Thu, Oct 22nd 2015 |
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I came across this thread while searching for information on vspec, which I chanced upon in the source when looking for a way to calculate dipole matrix elements at DFT level.
I simply added the vspec keyword to the dft input block, which gave me a .vspec file at the end of the calculation. This contains the energy difference between pairs of molecular orbitals, what appears to be expectation values of x, y, and z position operator and oscillator strengths. From looking at dft_input.F, I see there are options to specify alpha or beta spin and number of excitations.
I would also to be interested to know if this feature is ready for use. The output I have obtained certainly looks reasonable.
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Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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Forum Regular
Threads 4
Posts 209
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| 5:08:22 AM PDT - Sun, Oct 25th 2015 |
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Hi, Yes. The vspec feature for scalar calculations can be used. I'll document it.
For an open shell calculation:
vspec alpha nocc nvir beta nocc nvir
For a restricted calculation:
vspec nocc nvir
Let me know if there are any issues.
Best,
-Niri
niri.govind@pnnl.gov
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Clicked A Few Times
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| 10:58:39 AM PDT - Sun, Oct 25th 2015 |
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Hi Niri,
Thank you very much. I will be making a lot of use of this!
Best,
Mark
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