Notebook D, using OPLS 4 parameters fitting

[UlughBeg86]

Dear Pablo,
I want to fit MD (k_i=0, i=1,2,3,4) to DFT potential energies profile using OPLS force field, in which 4 parameters are required to fit for one type of dihedral angle. But I found that there were best fitting curve with 7 parameters. So I would like to get OPLS 4 parameters with small RMSE value.

Thank you in advance,
Rishat

[pablo-arantes]

Hi Rishat,

Thank you for reaching out. I’m not completely sure I understand your question, but if you already have both the MM curve and the DFT curve, you can use Notebook 4 to fit the dihedral energy profile. That notebook will give you the optimized parameters you need to include in the force field.

If you can share a bit more detail about the specific issue you’re encountering, I’ll be happy to help further.

Best regards,
Pablo

[UlughBeg86]

Hi Pablo,
The OPLS force field has 4 parameters for each dihedral angles. I did use Notebook 4 to fit dihedral energy profile. But I found that with 4 parameters, the fitting is not good compare to using 6 and 7 parameters. Do you have a solution ?

Best regards,
Rishat