My complex was converged for Maximum force and RMS force at the 45th step when using the SDD basis set, and then remove from convergence after 20 steps. Now, 183 steps have been completed but the complex is not fully converged yet. Still, Is there any chance to be converged fully again? I have checked the values of the Maximum force and RMS force: it is not decreasing gradually, instead moves back and forth in alternate subsequent steps. What should I do next?
Hi Maah Nasir ,
your problem is not really clear to me.
First, which functional were you using (B3LYP).
Then, the optimisation converged within 45 cycles? Did you optimise further and then the structure got unstable again?
It might oscilliate. You could change some parameters for step length etc or restart the geometry optimisation from the last structure. Sometimes a new approximated hessian could be helpful.
Good luck and kind regards
Conrad
Hi Maah Nasir ,
Are you using Gaussian/Gaussview? If so there will be four force categories that must all be below the threshold and will read out as YES for the optimization to have completed.
If you're using GV you can open the log file at any time to "watch" the optimization cycles and make sure it isn't running off and doing something silly, which can happen, especially if there are multiple conformational minima. If so, you might want to kill the calculation, adjust the structure to something more reasonable, and restart.
Hope this helps let us know how it goes!
Cheers, Amy
- Badges
- Science topic