READ_PARAMETERS -- read parameters library

FILE = <string:1>	'default'	partial or complete filename
DIRECTORY = <string:1>	''	directory list (e.g., 'dir1:dir2:dir3:./:/')
ADD_PARAMETERS = <logical:1>	off	whether to add new parameters to existing ones

Description:

This command reads the parameters from the parameter library, such as the CHARMM 22 parameter file for proteins with all atoms [MacKerell et al., 1998]. This file contains the values for bond lengths, angles, dihedral angles, improper dihedral angles, and non-bonded interactions. MODELLER relies on slightly modified CHARMM-22 parameters to reproduce the protein geometry in the MODELLER environment. For example, for the default non-hydrogen atoms model, the $\omega$ dihedral angle restraints are stronger than the original CHARMM 22 values which apply to the all-hydrogen model. For a sparse discussion of the parameter library, see the FAQ Section 1.8, Question 17.

If ADD_PARAMETERS is on, the new parameters are added to the existing parameter list, otherwise the contents of the new parameter file replaces the old one.

The filename for the library is DIRECTORY/FILE.

Example: See PATCH command.