If you have GAMESS ab initio quantum chemistry package, you can use it instead of Gaussian. You need to set some environment variables that will be used by GRRM program as follows:
alias subgms rungms
setenv gmstmp $HOME/scr
setenv gmsscr1 ./
setenv gmsscr2 $HOME/scr
where subgms is an alias of "rungms" command (you may need to specify the full path of your rungms as '/usr/local/gamess/rungms', for example), gmstmp is a local temporary directory required by GAMESS, and gmsscr1 and gmsscr2 are scratch space directories used by GAMESS. (You may need to ask your system administrator.)
You need to prepare two GRRM input files, XXX.com and XXX.tmp. XXX.com is an input file. You must declare "%link=gamess" in the first line of the input file. XXX.tmp is a template file for a GAMESS input file; GRRM program will generate a GAMESS input file from the template on demand and then call rungms.
Sample input files for a ADDF calculation of formaldehyde at the MP2/6-31G level of theory are:
C 0.000000000036 0.000000000000 -0.631331321540
H -0.934113855006 -0.000000000000 -1.212877294329
O -0.000000000045 -0.000000000000 0.626493801819
H 0.934113855294 -0.000000000000 -1.212877293190
$CONTRL ICHARG=0 MULT=1 SCFTYP=UHF MPLEVL=2 RUNTYP=GRADIENT
NOSYM=1 MAXIT=200 ISPHER=1 $END
$SYSTEM MWORDS=200 $END
$BASIS GBASIS=N31 NGAUSS=6 $END
The template file is very similar to the GAMESS input, so that please see GAMESS user's manual for further usages.
NOTE THAT [Charge] and [Spin multiplicity] in the input file (XXX.com) are not used in the GAMESS program, and the corresponding parameters written in XXX.tmp, ICHARG and MULT, are actually adopted.
In a crossing point (MECI or MESX) calculation, another templete file, XXX.tmp_1, is needed for the second state. If "MO GUESS = mmm.ooo" option is used without the "Guess = Same" option (default: Guess = Different) in combination with the ModelF or OptX keyword, two MO files must be provided, i.e., mmm.ooo and mmm.ooo_1 for the first and second states, respectively.
Our tests were made with the version 11 AUG 2011 (R1).