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Re: How to do an unrelaxed SURFACE scan of a dihedral angle in DLC?

Alex Granovsky
gran@classic.chem.msu.su


Dear Bernhard,

the short answer is: it is impossible. Not because this feature
is not currently implemented but rather because it is impossible
to implement such a kind of scan correctly. You need to use plain
but well-defined Z-matrix for you scan.

Kind regards,
Alex




On Sat Mar 18 '17 10:54am, Bernhard Dick wrote
----------------------------------------------
>I want to scan along a torsional angle using DLC. If I do a relaxed scan, this works with the following $SURF and $ZMAT groups:

> $SURF NDISP1=5 DISP1=3.0 ORIG1=90.0 NSURF=1 $END
> $ZMAT DLC=.T. AUTO=.T. IFZMAT(1)=3,22,1,2,3 SCAN=.T. IFDMOD=1 $END

>However, if I change "RSURFACE" to "SURFACE", I get the error message

> NO ATOMS TO MOVE IN SURFACE MAPPING

> ADDRESS 0x0078FEF2 HAS INITIATED PROGRAM ABORT BECAUSE OF FATAL ERROR(S)

>So what do I need to do the get the unrelaxed SURFACE. (I dont want to use Z-matrix, since there seems to be some instability with the same example in Gaussian ZMT-coordinates (made with Chemcraft), and the surface definition:

> $STATPT METHOD=GDIIS NSTEP=30 IFREEZ(1)=15 $END
> $SURF NDISP1=5 DISP1=3.0 ORIG1=90.0 VECT1(15)=1 NSURF=1 $END

>I get the error

> ROUNDOFF ERROR IN BEND - STOP

> ADDRESS 0x008197DC HAS INITIATED PROGRAM ABORT BECAUSE OF FATAL ERROR(S)

>best regards,
>Bernhard

>


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