CCL: Optimization with B3lyp functional in DFT

 Sent to CCL by: "Jaime Martell" [jaime_martell*|*cbu.ca]
 Dear Senthil
 What this tells you is that HF and B3LYP yield different geometries,
 which is to be expected if you use different methods.  Why would you
 want to get the same results?
 Jaime
 -----Original Message-----
 > From: owner-chemistry+jaime_martell==cbu.ca()ccl.net
 [mailto:owner-chemistry+jaime_martell==cbu.ca()ccl.net] On
 Behalf Of
 Senthil kumar Krishnasamy supersenthil73_-_gmail.com
 Sent: March-27-12 10:48 PM
 To: Jaime Martell
 Subject: CCL: Optimization with B3lyp functional in DFT
 Sent to CCL by: "Senthil kumar  Krishnasamy"
 [supersenthil73^gmail.com]
 Dear all
 I had optimized the structures of Trifluoromethane sulfonyl fluride
 [CF3SO2F] and trifluromethane sulfonic acid [CF3SO2OH]   with Hartree
 fock method with equilibrium bond lengths and bond angles between the
 atoms. But the same compounds are optimized with B3lyp functional; I get
 a deviation from equilibrium bond length between carbon and sulphur
 atoms, sulphur and fluorine atoms of 0.02 , 0.05 , and 0.08
 respectively. I used the Keywords of int=ultrafine, geom. =conn,
 opt=vtight with B3lyp functional. I didnt get the equilibrium bond
 lengths for the above case.  The oxidation state of sulphur atom is
 followed by a value of 6 for both the compounds. I done the freq
 calculation for the same compounds by HF method and there is no
 imaginary frequency. What is the key word to be used to get the
 equilibrium bond length between carbon & sulphur atoms and sulphur &
 fluorine atoms in the optimization step using B3lyp functional?
 I expect the possible help from all.
 Thanks in advance
 By
 K. Senthil kumar
 Faculty of Physics
 HIndusthan College of engg & tech
 Coimbatore-32http://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt