Dear Modeller Team,

I am currently looking for a quick method for calculating the energy of protein structures. I understand that Modeller utilizes a simplified version of the CHARMM force field, which suits my needs, as I’m looking for a fast and approximate energy calculation.

I would like to print out each energy term, but with the current code I’m using, the Lennard-Jones and Coulomb terms are returning zero. Could you please advise on how to resolve this issue?

The code that I used: 

from modeller import *
from modeller.scripts import complete_pdb

# Initialize MODELLER environment (use Environ instead of environ)
env = Environ()

# Load topology and parameter libraries
env.libs.topology.read(file='$(LIB)/top_heav.lib')  # Heavy atom topology
env.libs.parameters.read(file='$(LIB)/par.lib')    # Parameter library

# Read in the protein structure
mdl = complete_pdb(env, '3VXU.pdb')

# Calculate energy
mdl.energy()

# Energy calculations are complete
print("\nEnergy calculation completed.")

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Thank you for your help.

Best,

Li