CCL: questions on convergence, restarting jobs, counterpoise
- From: "Saurabh S Chitnis"
<sschitnis-,-gmail.com>
- Subject: CCL: questions on convergence, restarting jobs,
counterpoise
- Date: Sun, 27 Nov 2011 17:02:07 -0500
Sent to CCL by: "Saurabh S Chitnis" [sschitnis _ gmail.com]
Hello,
I have three questions:
1. In many of my "opt" and "freq=raman" jobs, I find that
the calculation completes successfully with
the forces having converged but the displacements still being above the
convergence threshold. How
can this be fixed? I usually face this problem when using opt=verytight and
int=ultrafine.
2. Is there any way of restarting an analytic frequency job which has completed
but not converged?
3. Can the output of a counterpoise calculation (i.e. the Corrected total
energy) be interpreted as a
bond-dissociation energy between the two fragments?
Here are some details regarding the above questions:
theory: DFT (B3LYP, PBE1PBE and B3PW91)
basis-set: cc-pvtz and aug-cc-pvtz
systems being calcualated: P2Me4, [P2Me5]+ and [P2Me6]2+
for the couterpoise: I'm trying to get the P-P bond dissocation energy. So I
optimize the geometry as
per usual and then redefine the optimized P2Me4 as fragment1(Me2P) and
fragment2(PMe2) to run
the counterpoise calculation. The result should be the homolytic bond
dissociation energy right?
cheers
Saurabh