CCL:G: Gaussian IR frequency calculation

[André Farias de Moura <moura*|*ufscar.br>]

not really a Gaussian issue, the frequencies from the standard harmonic
 oscillator model need to be scaled. Scaling factor depend on your choice of
 basis set and level of theory, so you need to find out if anybody has ever
 published a scaling factor for your specific choices (rb3lyp/6-311++g(d,p)),
 otherwise you have to obtain the proper factor by yourself. for the
 unrestricted case, take a look at: J. Phys. Chem. A, 2005, 109 (12), pp
 2937–2941, for instance.
 best
 André
 On Sat, Mar 21, 2015 at 12:46 PM, Gustavo A Gotelli ggotelli*|*
 kaliumtech.com <owner-chemistry-.-ccl.net> wrote:
 >
 > Sent to CCL by: "Gustavo A Gotelli" [ggotelli- -kaliumtech.com]
 > Hi all!
 >
 > I'm using G03W for doing an IR frequency calculation using the 6-311g basis
 > set,
 > # opt freq rb3lyp/6-311++g(d,p) pop=savemixed geom=connectivity scf=tight
 >
 > The problem is that results are far from experimental data, with
 > differences around 300/400 cm-1 between calculated and experimental peaks.
 > I guess is because I'm using wrong parameters, perhaps the basis set.
 > Can somebody suggest how to get results that better fits experimental data?
 >
 > Thanks in advance
 > Gustavo
 >
 >
 >
 > -= This is automatically added to each message by the mailing script =->
 >
 >
 --
 _____________
 Prof. Dr. André Farias de Moura
 Department of Chemistry
 Federal University of São Carlos
 São Carlos - Brazil
 phone: +55-16-3351-8090