Are the force field files for OPLS/2020 available somewhere? I am performing MD simulations on molecules containing silicon using a customized force field. If OPLS/2020 is available, it would greatly save time. I would appreciate any help or guidance.
Reference:
OPLS/2020 Force Field for Unsaturated Hydrocarbons, Alcohols, and Ethers
William L. Jorgensen, Mohammad M. Ghahremanpour, Anastasia Saar, and Julian Tirado-Rives The Journal of Physical Chemistry B2024, 128 (1), 250–262.
DOI: 10.1021/acs.jpcb.3c06602
The parameters are available in the SI of the paper you linked, but as for assigning them to specific molecules as far as I’m aware specific GROMACS files for that aren’t available online. When I used this FF I had to do it myself. Might I recommend the DL_field software for this? It’s used for automatic FF parameter assignment if you have an initial structure. OPLS/2020 is not available (up to OPLS/2005 is) but the software makes it easy to take OPLS2005 and change specific dihedrals/vdW parameters (via udff file), which is what you’d do to make files for OPLS/2020 as not much is changed. If the molecule is small honestly you could use it to automatically assign OPLS2005 and then manually change a few parameters.
You need to apply to use the software on the DL_field website but this takes one minute, and then you’ll get an email with the source code. Instructions on how to install are in the README it’s very easy. There are also tutorials online for the software, and more comprehensive ones will be released hopefully in the next month. Feel free to reply if you have any questions if you do decide to use it.
Thank you very much for your comments and useful information. I currently use PolyParGen/LigParGen for my setup, but they have some limitations. I will look into DL_FIELD as soon as I have time to work on it.
I’m not sure about PolyParGen but LigParGen has issues with assigning correct charges. I often get net charge on molcules which shouldn’t have. DL_FIELD doesn’t have this issue. There’s also Foyer which is part of MosDeF but I haven’t used it