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EE-EOM-CC open-shell system

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Member
Registered: May 2016
Posts: 1
Hello everyone,
I want to calculate the energy of lowest excited state of LiFH, which is an open-shell system.
Can it be done by EE-EOM-CC with Q-chem? And what's the difference when dealing with open-shell system.
Administrator
Registered: Sep 2007
Posts: 175
Yes, it can be done. You first need to figure out what you want -- what is the sysme multiplicity, symmetry, etc. Seems like your system has doublet multiplicity, so there might be several different ways to look at excited states.

I suggest to first run simple Hartree-Fock, analyze MOs, then run CIS to get an idea of what lowest excited states might be. You might be able to describe excited states by the following:
Do EOMIP from LiFH-.
Do EOMEA from LiFH+
Do EOMEE from LiH.

Which method is most reliable depends on the type of the excited state.
See the following tutorial (soon to appear in Rev. Comp. Chem.) for guidance:
http://hogwarts.usc.edu/~krylov/OpenShell.pdf.gz

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