RE: Gaussian Convergence failure!



Yes, qc is often needed for such systems (namely S-Fe bonding). One usually
 starts with a HF calculation and a small basis, then increases the basis
 using options scf(qc,conver=8), then b3lyp calculation (with the same
 options)
 pierre.vitorge at.at cea.fr
 -----Message d'origine-----
 De: zborowsk at.at chemia.uj.edu.pl [mailto:zborowsk at.at
 chemia.uj.edu.pl]
 Date: vendredi 9 mai 2003 14:35
 Ŕ: chemistry at.at ccl.net
 Objet: CCL:Gaussian Convergence failure!
 Dear WIlliam
 I am not sure where your problem is, because you did not attach your input
 gaussian file with the structure of the molecule.
 But, if I have a problem with convergence in Gaussian
 (it is true especially for metal complexes)
 I usually use the QC option in SCF calculations
 So, write "SCF=QC" in your input file.
 Unfortunately you will need more time for your calculations :-(
 Best regards
 Kzys
 > Dear CCLers,
 >
 > After several Convergence failure (I changed conformations), what others
 > I can do for it? My system is about 20 heavy atoms, include one benzal
 > group in the end, and one Fluorine one Sulfur. After B3LYP/3-21G
 > optimized, it can not convergence at B3LYP/6-31+G(D) level. Could
 > anybody give me suggestion. I will summarize the result. Thank you.
 >
 > Best
 >
 > -------------------------
 > William Wei
 > Faculty of Pharmacy
 > 19 Russell Street
 > Toronto, ON. M5S 2S2
 > Tel: 1-416-946-8469
 > Fax: 1-416-978-8511
 > Email: william at.at phm.utoronto.ca
 >        william.wei at.at utoronto.ca
 > Http://phm.utoronto.ca/~william
 >
 >
 Krzysztof Zborowski
 Faculty of Chemistry
 Jagiellonian University
 3 Ingardena Street
 30-060 Krakow,
 Poland
 phone: +48(12)632-4888 ext. 2064 or 2067
 fax:  +48(12)634-05-15
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