TORSION PROPER

 NAME
TORSION – Read proper torsion potential

 SYNOPSIS
TORSION PROPER
...
typ1  typ2  typ3  typ4  $K_{\phi}$  $n$  $\gamma$
...
END

 DESCRIPTION
typ1, typ2, typ3 and typ4 are four character strings, not to exceed 7 characters, indicating the atom types of the four atoms involved in the torsion interaction (a x string is taken to be as a wild card indicating $any$ atom). The torsional axis, according to the ORAC convention is the one connecting the $type2$ and $type3$. The parameters $K_{\phi}$ and $n$ and $\gamma$ are defined in Eq. 4.3. $K_{\phi}$ is in unit of Kcal mol$^{-1}$; $n$ is an integer indicating the number of minima(maxima) for 360 degree rotation about the torsional axis; $\gamma$ is given in degrees and can be either 0.0 or 180.0.

 EXAMPLE

TORSION PROPER
x    c    ca   x        3.6250   2.0  180.0 
x    cw   na   x        1.5000   2.0  180.0
ct   ct   os   ct       0.3830   3.0    0.0
ct   ct   os   ct       0.1000   2.0  180.0
END