I have a complex that contains transition metals. I am doing parametrization and building the force field. I have one question about the frcmod file.

In the file, There are non bond paramters that are written like that.

OH 1.7210 0.2104
CT 1.9080 0.1094

When I googled it, I found that the numbers are the radius and well depth parameter, respectively. But I dont know, how can I measure these values, and I am not sure if I will need the van der waals equation or not ?

$$E_{VDW} =4 \sigma [1/4(r_0/r)^{12} - 1/2 (r_0/r)^{6}]$$

  • $\begingroup$ This is a duplicate - and yes, you'll need to get both from a potential energy curve. $\endgroup$ Apr 4, 2022 at 13:30
  • $\begingroup$ @GeoffHutchison Thanks for your help. I tried to look for all the answer related to this question, but I have some doubt, because they use water dimer or helium dimer. 1- In my case, I have a complex, and it contains transition metal in the center and this transition metal form 6 bonds with Nitrogen. Therefore, I don't know which distance should I use to do the scan and fit the equation ? 2- I saw the tutorial to use psi4numpy. But After I form the potential energy curve, I don't know what should I do next to get the values that it is written in frcmod (mentioned in the post) $\endgroup$ Apr 7, 2022 at 10:31