CCL:G: G09 ReadOptimize question

Hi Manuel,

If you want to optimize the position of H-atoms only, keeping other atoms intact then one way is to do partial optimization. you can use

# popt b3lyp/sto-3g

as your route section. You need to put a -1 after the atom symbol, for the atoms you want to keep frozen and 0 for the atoms which are needed to optimize. You can search the gaussian manual for details about "popt" option.

Hope this will help.

Good luck,

Mehboob

On Tue, Apr 24, 2012 at 11:33 AM, Manuel Fernandes 0occam]^[gmail.com <owner-chemistry++ccl.net> wrote:

Hi everyone,

Silly question. I am currently trying to use G09 to optimize the H positions on a structure of interest without success. I have the following in the input file:

**************************************************************
%chk=di3.chk
%nproc=4
# B3LYP/STO-3G Opt=ReadOpt

Di3 Restraints Test Calc

0 1
S       4.539427   14.265382    4.065973
S       7.312779   16.132727    2.561653
.
.
H       5.359781   20.854661    8.778371
H       4.984391   21.577421    7.214152

atoms=H notatoms=C N O S
**************************************************************

With this I get the following error:

**************************************************************
---------------------------
# B3LYP/STO-3G* Opt=ReadOpt
---------------------------
QPErr --- A syntax error was detected in the input line.
# B3LYP/STO-3G* Opt=ReadOpt
                   '
Last state="OPT1"
TCursr=45589 LCursr=   20
Error termination via Lnk1e in /home/gaussian//g09/l1.exe at Tue Apr 24 09:33:
Job cpu time: 0 days 0 hours 0 minutes 0.1 seconds.
File lengths (MBytes): RWF=      5 Int=      0 D2E=      0 Chk=      1 Scr=
**************************************************************

G09 seems to indicate that the issue is with ReadOpt but I am using the option as advertised in the G09 manual or at least I think so. I've also tried ReadFreeze and ReadOptimize. [http://www.gaussian.com/g_tech/g_ur/k_opt.htm]

Any ideas?

Thanking you in advance,

Manuel Fernandes