# Standard normal mode calculation.
#
from MMTK import *
from MMTK.Proteins import Protein
from MMTK.ForceFields import Amber94ForceField
from MMTK.NormalModes import VibrationalModes
from MMTK.Minimization import ConjugateGradientMinimizer
from MMTK.Trajectory import StandardLogOutput
from MMTK.Visualization import view
# Construct system
universe = InfiniteUniverse(Amber94ForceField())
universe.protein = Protein('bala1')
# Minimize
minimizer = ConjugateGradientMinimizer(universe,
actions=[StandardLogOutput(50)])
minimizer(convergence = 1.e-3, steps = 10000)
# Calculate normal modes
modes = VibrationalModes(universe)
# Print frequencies
for mode in modes:
print mode
# Show animation of the first non-trivial mode
view(modes[6])