Hi all, First of all Axel : using a much greater cutoff (90 Ryd) with BLYP, the BDE increased by 20 kcal/mol (!!) to 264 kcal/mol, bringing the value within 8 kcal/mol of the experimental. Thanks for your valuable input ! I'll try increasing the cutoff for other pseudos as well and report if there is any improvement. Also I plan to increase the cutoff further with BLYP and check for convergence and hopefully a further improvement in the BDE value.
Miguel, the vibrational frequency of CO is about 2200 cm-1, which relates to a zero-point correction of 3.1 kcal/mol (ZPE = 0.5*h*nu), so that is definitely not the reason for the huge discrepancy. Prasenjit, I did try the settings you suggested, but got a BDE of 271.6 kcal/mol (the only change between your input file and mine was a upward revision of ecutrho, and the BDE changed by only 0.1 kcal/mol). Thanks everyone for your inputs. ----- Original Message ----- From: "Miguel Mart?nez Canales" <[email protected]> To: <pw_forum at pwscf.org> Sent: Thursday, September 07, 2006 8:50 AM Subject: Re: [Pw_forum] Bond dissociation energy of CO (gas-phase) > Hello everybody, > > I have a small naive question with respect to the discrepancies Ameya is > getting. Being C and O pretty light elements, and because the dissociation > energies he is getting is always (except for BLYP) around 10-15 kcal/mol, > ?could this be caused because he is neglecting the zero-point energy? > > -- > ---------------------------------------- > Miguel Mart?nez Canales > Dto. F?sica de la Materia Condensada > UPV/EHU > Facultad de Ciencia y Tecnolog?a > Apdo. 644 > 48080 Bilbao (Spain) > Fax: +34 94 601 3500 > Tlf: +34 94 601 5437 > ---------------------------------------- > > > "If you're a mad scientist, you can use > GPLv2'd software for your evil plans to > take over the world" > > Linus Torvalds > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum
