How do I convert the parameters of Buckingham potential to the parameters of LJ

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GROMACS version:2018.8
GROMACS modification: No

Hello everyone,

I want to convert the parameters of Buckingham potential (A,B,C6) into the parameters of LJ potential (C6,C12). Is there any way to achieve this?

I noticed that one of the commands in gromacs was

gmx sigeps

There’s a line in the manual about this command

In addition, it makes an approximation of a Buckingham potential to a Lennard-Jones potential.

I tried this by substituting the Buckingham potential parameters (A,B,C6) from the literature

gmx sigeps -A 200000 -B 34.07 -C 0.005 -o output.xvg

However, it also does not produce specific LJ potential C6,C12 values, but produces the following data:

image
image982×589 103 KB

So I wonder if this command can get the LJ potential parameters (C6,C12) converted from the Buckingham potential parameters (A,B,C6)? If not, how can I get it?
I’m feeling quite confused at the moment, and I would greatly appreciate it if someone could kindly help me. Thank you so much!