Saturday, 12 July 2014

Analysis and visualization of excited states

My drive to create pretty orbital pictures lead to two new papers, which I quite like: "New tools for the systematic analysis and visualization of electronic excitations" Part I: Formalism and Part II: Applications. Actually, a number of interesting things happened on the way and people seem to like it so far.

One of the interesting points is the discrepancy between the transition and difference density matrices. Both should give you a compact representation of the transition - but not necessarily the same one ...

For example these are the hole and particle densities (computed from the 1-particle transition density matrix) of the first two singlet excited states of adenine (using Jan's extension of my VMD plotting script) deriving from a ππ* and a nπ* state.

For comparison the attachment/detachment densities (computed from the difference density)

 What you can see is that the attachment/detachment densites are "bigger" than the particle/hole densities. The difference is that many-body effects and orbital relaxation are only included in the latter case giving additional contributions. You can look at this in more detail by analyzing the individual orbitals these are composed of, the "natural difference orbitals". Maybe I'll show that in the next post. Or check out the articles - I think for the first 30 days you can even download them freely.

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