*From*: Uli Salzner <uli $#at#$ smaug.physics.mun.ca>*Subject*: summary spurious intergrated densities*Date*: Wed, 29 Nov 1995 12:13:45 -0330 (NST)

any thnaks to everyone who replied. Your comments helped al lot. Here is a summary of the answers I received: Hi there, I have encountered the same problem a few times, and what you have to do is to alter the grid over which the integrals are calculated. Refer to pages 6 and 9 of the "New Methods and Features in Gaussian 92/DFT" Release Notes for a complete description. Basically one way to correct this is to compute the integrals using a finer grid. Thiscan most easily be accomplished by using the Int=FineGrid keyword. (gives about 7000-9000 points per atom compared with the default of about 3000 points per atom with Int=Normalgrid). If this fails you can define a numnber of even finer grids by following the Grid Control Appendix in the Releas Notes on pg 9. Stephen Decker decker $#at#$ jcvsparc.chem.ualberta.ca Dept. of Chemistry, Univ. of Alberta, Canada You need to upgrade to G94...these problems have been fixed...of get G92 Rev Level F. Regards.. John -- John M. McKelvey email: mckelvey $#at#$ Kodak.COM Computational Science Laboratory phone: (716) 477-3335 2nd Floor, Bldg 83, RL Eastman Kodak Company Rochester, NY 14650-2216 bernhard $#at#$ quant1.chemie.uni-leipzig.de Subject: Re:DFT/spurious integrated densities Hi, few weeks ago i struggle over the same problem. I got the tip to add the keywords SCF=NoVarACC INT=FineGrid which work in ca. 90% of all cases (using B3LYP). The first is not fully known to me (didn't find the keyword in the g92 manual), but i think it enhance the accuracy of the integrals or is related to this point, the second point results in better numerics while integration. Don't take it for good, i'm just a starter... If this doesn't work, then a slight alteration of the geometry helps sometime (nearly in all remaining cases). Bernhard Eck Dr. Salzner, We have seen this problem with G92 and have made a couple of changes which you can use with G92 that improve the situation dramatically. Add the following Int=FINEGRID to your calculations. This may be sufficient as it improves the integration accuracy. If not also add SCF=NOVARACC which turns off using loose integration cutoffs on early SCF iterations. Both of these will increase computation time but have proven successful enough that INT=FINEGRID is standard in G94. We have modified the cutoffs for early iterations and seldom see this problem with G94. Douglas J. Fox Director of Technical Support help $#at#$ gaussian.com