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Re^2: freezing bond length in IRC job

Alex Granovsky
gran@classic.chem.msu.su


Hi Jim,

well, there are lots of people (including myself) who believes
that INTRINSIC REACTION COORDINATE does not have much sense at
all - e.g., unlike stationary points on PES, it is non-invariant
with respect to arbitrary diffeomorphic transformation of
coordinate system. More precisely, if you calculate IRC, then
transform coordinates, calculate IRC in new coordinates, and then
back-transform coordinates, the two IRCs will be different.

Regards,
Alex

On Mon Jun 21 '10 6:37pm, Jim Kress wrote
-----------------------------------------
>Doesn't "freezing" a coordinate in an INTRINSIC REACTION COORDINATE calculation defeat the whole purpose of performing the INTRINSIC REACTION COORDINATE calculation?  After all, you are looking for a reaction path which, if you "freeze" one coordinate, will not be a reaction path, it will be just an artificial construct that has no real physical meaning.

>Look here:

>http://blake.lsmc.u-bordeaux.fr/Ampac/algorithms.html#pathalgohttp://blake.lsmc.u-bordeaux.fr/Ampac/algorithms.html#pathalgo

>for some deeper insight.

>On Sun Jun 20 '10 9:29pm, Eldar Mamin wrote
>-------------------------------------------
>>Dear Fireflly Users,

>>Can I freez bond length in IRC job?

>>To define molecule I use Z-matrix, and function ifreez to make coordinate frozen. Following that way I get Saddle point, but during runtyp=irc  no coordinate is kept frozen.  

>>Can anyone help me?


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