Problematic Convergence template (Gaussian):
The strategy is to describe solving convergence problems in a large
production job by converging an SCF on a smaller approximate version
of the job, using this as an initial guess for a moderate sized
approximation, using this as initial guess for a larger job, etc.,
until you have a very good initial guess for the production job.
- set up input file (test1.com) for the lowest level job
- specify the job type as RHF/STO-3G
- be sure to provide a specific name (fe2co.chk) for the
checkpoint file
- run the job using the input file above as:
- run.s test1
- if you are running in a scratch space different from where
your input and output files are stored, ensure that your checkpoint
file is copied back to the input/output directory for future use.
- copy over the previous input file (test1.com) to a new file
(test2.com)
- change the job type to RHF/6-31G
- run the new job as:
- run.s test2
- make sure the checkpoint file (fe2co.chk) is copied to the
scratch directory at the start of the job, and returned to the
input/output directory at the end
- copy over the previous input file (test2.com) to a new file
(test3.com)
- change the job type to B3-LYP/6-31G
- run the new job as:
- run.s test3
- make sure the checkpoint file (fe2co.chk) is copied to the
scratch directory at the start of the job, and returned to the
input/output directory at the end
- copy over the previous input file (test3.com) to a new file
(fe2co.com)
- change the job type to B3-LYP/6-31G*
- run the new job as:
- run.s fe2co
- make sure the checkpoint file (fe2co.chk) is copied to the
scratch directory at the start of the job
************************************ test1.com ****************************
%chk=fe2co.chk
#P RHF/STO-3G
Tough convergence case
0 1
Fe1
Fe2 Fe1 R1
C Fe1 R2 Fe2 A1
O C R3 Fe1 A2 Fe2 A3
Variables:
R2=2.382524
R3=1.143116
A1=75.336242
A2=63.720728
A3=0.00
Constants:
R1=2.52
*************************************** end *******************************