To modify force field defaults in Biosym...
In this module, we will be using Biosym software to perform force field calculations on polymer molecules. For this purpose, we should use the pcff force field rather than the default cvff force field. This can be changed manually within InsightII, as described in Homework #1. To make this change more permanent, you can define pcff to be the new default by adding these lines to your .cshrc file:
#Use pcff forcefield as default
setenv FORCEFIELD pcff.frc
setenv INSIGHT_POTENTIAL_TEMPLATES pcff_templates.dat
setenv RESIDUE_LIBRARY pcff.rlb