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Date: Thu, 22 Jun 2006 07:00:00 +0200
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Forum: ADF and ADF-GUI discussions

Topic: How to fix this kind of error in freq calcs.

Link	Post Time	Author	Message Excerpt
206	21 Jun 2006, 06:06 PM CEST	Alexei Yakovlev	The problem here that you have two almost degenerate electronic states here. During numerical differentiation it is possible that some of the displaced geometries are in one state while the others are in the other state. This leads to inconsistent gradients of the energy and, as a consequence, incorrect frequencies. The analytical second derivatives method is supposedly free from this so I'd suggest giving it a try in a couple of weeks when ADF2006 is out. I don't have an immediate solution for the numerical frequencies. You may want to try to increase the symmetry of the system and/or try FREQUENCIES SYMM option (see manual for details). Alexei
207	22 Jun 2006, 05:06 AM CEST	bluemolecule	Thanks for your analysis. I've been using "FREQUENCIES SYMM" in these freq calculations but haven't seen any improvement. The target I optimize is OScCO(2A') with planar geometry---the highest possible symmetry for this molecule. btw, how soon will be ADF2006 available ?

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Received on 2006-06-22 07:00:00