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Cannot set up force fields upon save



I’m a student trying to create some models for a research project on neurotransmitters interacting with functionalised polymers. When I save my progress and load it up however, the force field optimization and auto optimization doesn’t work at all.

The software says it’ll revert back to UFF, and that’s all it does. It just keeps reverting back to UFF every time I press ctrl+alt+o without actually working.

If somebody could please help me out with this I’d highly appreciate it. I really need this software to work for a few papers I mean to publish.


I don’t quite understand what you’re trying to do, or what molecule you’re trying to optimize.

If you have the optimization set to use MMFF94 and have elements in your molecular that are not in MMFF94, it will naturally revert to UFF, a universal force field. That has nothing to do with saving or anything else - it will happen based on your molecule and the force field chosen in the options.

Can you post the molecule file?


What’s happening is when I load up a model I have created and saved in .cml, I cannot apply any force field optimizations to it, be it MMF94 or UFF, whereas the model was optimized in MMF94 before saving.

Here are some of the files I’ve been working on: