I am working in Gaussian 16 for an Optimization job where a hydroxyl radical is attacking. However, I need to get an optimized reacting complex optimized structure. The whole structure is neutral having a radical electron in hydroxyl oxygen instead of a negative charge. I tried it several times but it is producing errors with the following message:
Error on total polarization charges = 0.05662
SCF Done: E(UB3LYP) = -383.260168042 A.U. after 129 cycles
NFock=128 Conv=0.11D-04 -V/T= 2.0096
= 0.0000 = 0.0000 = 0.5000 = 0.7523 S= 0.5011
= 0.000000000000E+00
SMD-CDS (non-electrostatic) energy (kcal/mol) = 3.38
(included in total energy above)
Annihilation of the first spin contaminant:
S**2 before annihilation 0.7523, after 0.7500
Convergence failure -- run terminated.
Error termination via Lnk1e in C:\G16W\l502.exe
Can anyone help me to get on from this error? What is the meaning of this error and how can I resolve it?
With best regards including advanced thanks.
Keshab K. Adhikary
Keshab Kumar Adhikary Instead of scf=tight, try using scf=qc or scf=xqc for maybe two(more if required) optimization cycles, and then switch back to scf=tight and continue the optimization.
You can also try using scf=conver=3 or 4, which relaxes the threshold values for Force and Displacement, but I am not sure if this works for Gaussian 16. You can try!
Hi Keshab Kumar Adhikary ! Could you please provide the keywords that you are using. If You have not done it yet, I recommend first to add scf=xqc. Once you reached the step 128 in the SCF process, it tells Gaussian to use the quadratically convergent SCF algorithm. It is slower but you will be able to converge the system in most of the cases.
Hello sir,
I will recommend to use scf=xqc and first try to optimize in gas phase then go for the solvent phase.
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