CCL: Doubt on Optmization Output
- From: Brian Salter-Duke <b_duke..bigpond.net.au>
- Subject: CCL: Doubt on Optmization Output
- Date: Sun, 29 May 2011 09:41:55 +1000
Sent to CCL by: Brian Salter-Duke [b_duke#,#bigpond.net.au]
On Sat, May 28, 2011 at 05:10:43PM -0400, Guilherme Luis Cordeiro
> Sent to CCL by: "Guilherme Luis Cordeiro"
> Dears members,
> I started performing an optmization on a flavonoid system containing around
30 atoms surrounded by 3 ethanol molecules. First calculation began with AM1
method, then I used this as a starting point for a new minimization with
B3LYP/3-21G model chemistry. The job finished like this:
> Item Value Threshold Converged?
> Maximum Force 0.000004 0.000450 YES
> RMS Force 0.000001 0.000300 YES
> Maximum Displacement 0.041333 0.001800 NO
> RMS Displacement 0.006043 0.001200 NO
> Predicted change in Energy=-2.049104D-07
> Optimization completed on the basis of negligible forces.
> -- Stationary point found.
> The geometry obtained, then, is being used on another minimization
> with B3LYP/6-31G. Should restart it all over? What does mean the
> "negligible forces" term?
What it says. Look at the Maximum Force and RMS Force values. They are
very small. The surface is very flat so the forces are small and the
predicted displacements for the next step are large and never going to
get small, so it stops. You can try restarting with a different basis
set. It might work.
> Thanks in advance.
> Guilherme Cordeiro.>
Brian Salter-Duke (Brian Duke)
626 Melbourne Rd, Spotswood, VIC, 3015, Australia.
Email: b_duke_-_bigpond.net.au Phone: 03-93992847