Up: Writing a Parameter Previous: How the Type-based
The first example shows how to
set the energy constants of all improper angles involving
tyrosine residues to 500 kcal mol
rad
. The
periodicity and the equilibrium constants are untouched by
the TOKEn keyword.
parameter
improper ( resname tyr ) ( resname tyr )
( resname tyr ) ( resname tyr ) 500 TOKEN TOKEN
end
In the next example, the energy constants of all bonds are
set to 400 kcal mole
Å
:
parameter bond ( all ) ( all ) 400. TOKEN endIn the next example, the energy constant for the
torsion
angle for X-Pro peptide bonds is set to 500 kcal
mole
Å
. This example
applies only to parameter files that define the 
torsion angle as a dihedral angle, such as ``toph19.pro" or
``tophcsdx.pro".
parameter
dihedral ( name CA and resname * ) ( name C and resname * )
( name N and resname PRO ) ( name CA and resname PRO )
500 TOKEN TOKEN
end
The last example is similar to the previous one, except that,
in addition to increasing the energy constant, the periodicity
is set to one and the equilibrium angle is set to 0
;
i.e., only trans prolines are allowed.
parameter
dihedral ( name CA and resname * ) ( name C and resname * )
( name N and resname PRO ) ( name CA and resname PRO )
500 1 0.
end