| 1:12:30 PM PDT - Mon, Jun 12th 2017 |
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Hello,
I am wondering if there is a way to set the spin states (# of unpaired spins and direction up/down) of individual atoms that would provide more control over specifying an overall system multiplicity (ie. using mult or nopen depending on the theory used). I am interested in studying electron transfer (ET) between two species. For my system the pre- and post-ET states have the same overall multiplicity. I would like to run energy calculations (and perhaps geometry optimizations) with the transferred electron in the pre- and post- ET configurations.
My system, PuO2 (2+) and HS (1-) has the following conditions...
Pre-ET: 2 unpaired spin (up) on the Pu(6+) and no unpaired spin on the S. This would be mult=3 or nopen=2 depending on the theory used (dft vs hf).
Post-ET: 3 unpaired spin (up) on Pu (now 5+) and 1 unpaired spin (down) on the S (part of a now neutral HS). nopen for this system would be 4 and the multiplicity would actually be 3 I think... (3 up - 1 down +1 = 3). I have tested mult=4 just to see what happens too.
For my pre-ET configuration, odft calculations show Mulliken spin values of 1 on the S and a lower than expected values for Pu. uhf calculations show S spin of -1 with Pu much higher than expected. I want to see what the energy looks like if there is ~0 spin on S...
If I run the post-ET configuration as an uhf calculation with nopen 4, I get a positive/up spin of 1 on the S instead of -1 and a lower than expected value on Pu. If I do a odft calculation with mult=4 I get the same thing. If I do mult=3 I just get the same result as my pre-ET state.
Is there a way, using either with dft or hf, to specifically designate the # of unpaired spins and their directions (up/down) for individual atoms? At the moment the treatments I have tried with the overall mult/nopen are not providing enough control.
Thank you,
Will
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