On Fri Jun 1 '12 9:27am, David wrote
>I have a series of molecules with flexible and rigid units in. They are typically up to 100 to 150 atoms (occasionally larger). I am having trouble getting them to an equlibrium structure using RHF / 6-31 basis set. They just keep on reaching the time limit (which I have tried increasing to 3600 and then 9999) but they do not find the equilibrium geometry - so no hessian is calculated.
>The options I am using in the job are:
> WARNING! YOU ARE USING OUTDATED VERSION OF THE FIREFLY!
> PLEASE CHECK FIREFLY HOMEPAGE FOR INFORMATION ON UPDATES!
> EXECUTION OF FIREFLY BEGUN 19:26:21 LT 31-MAY-2012
> ECHO OF THE FIRST FEW INPUT CARDS -
> INPUT CARD>!HyperChem Input Job
> INPUT CARD> $CONTRL SCFTYP=RHF RUNTYP=OPTIMIZE ICHARG=0 MULT=1 COORD=CART $END
> INPUT CARD> $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 $END
> INPUT CARD> $SYSTEM MWORDS=100 TIMLIM=9999 $END
> INPUT CARD> $CONTRL NZVAR=1 MAXIT=999 fstint=.t. gencon=.t. d5=.t. $END
> INPUT CARD> $STATPT METHOD=GDIIS HSSEND=.T. $END
> INPUT CARD> $ZMAT DLC=.t. AUTO=.t. $END
> INPUT CARD> $SCF DIRSCF=.TRUE. $END
> INPUT CARD> $p2p p2p=.t. dlb=.t. $end
> INPUT CARD> $p2p mxbuf=2048 $end
> INPUT CARD>
>I am running on 64-bit windows 7 with a i7 Processor.
>My command line options are using the job parallelised with 8-cores. I get the following in the output file.
>Warning: HTT is enabled, bitmask of physically unique cores is 0x000000AA
> SMT aware parts of program will use 2 threads.
> Creating thread pool to serve up to 128 threads.
> Activating Call64 option.
> Using 64-bit DGEMM by default.
> Loading P2P interface library... loaded successfully (version 1.9).
> Initializing P2P interface... topology done.
> BASIS OPTIONS
> GBASIS=N31 IGAUSS= 6 POLAR=POPLE
> NDFUNC= 1 NFFUNC= 0 DIFFSP= F
> NPFUNC= 0 DIFFS= F
>Can anyone give some advice about the best minimisation strategy to find equilibrium geometry as fast as possible? I had pre-optimised the structures with PM3 on hyperchem to RMS energy 0.0001 kcal/mol and then saved as firefly output.
>Should I perhaps be doing the calculation with smaller basis set first?
>I am actually interested in vibrational frequencies. Is there any benefit from a frequncy point of view in using a larger basis set?
>Another factor that might contribute to my problem is that I am unsure whether my restart procedure is correct. I have been going to the last structure generated in the timed out geometry search in the output file and cutting and pasting just the coordinates into the new input file for restart. Then I resubmit the job. I presume this will not have previuosly calculated gradient in etc so I wonder if this means the restart is losing a sense of 'which way is up?? Is there a more efficient way to restart?
>Any advice very welcome. I apologise if this is a basic question. I am quite new to Firefly.
[ This message was edited on Fri Jun 1 '12 at 12:56pm by the author ]