Syntax

RESTraints

DIHEdral { $<$restraints-dihedral-statement$>$ } END is invoked from the main level of X-PLOR. Invocation automatically turns on the CDIH energy flag (Section 4.5).

$<$restraints-dihedral-statement$>$:==

ASSIgn

$<$selection$>$ $<$selection$>$ $<$selection$>$ $<$selection$>$
$<$real$>$ $<$real$>$ $<$real$>$ $<$integer$>$ adds a new dihedral angle to the restraints-dihedral database. The four selections have to be unique; i.e., each selection must select exactly one atom. The selections determine the four atoms that specify the dihedral angle. The first $<$real$>$ number specifies the energy constant ($C$) in kcal mole$^{-1}$ rad$^{-2}$, the second $<$real$>$ number specifies the angle in degrees to which the dihedral angle is restrained (${\phi}_o$), the third $<$real$>$ number specifies the range around the restrained angle ($\Delta \phi$), and the $<$integer$>$ number specifies the exponent ($ed$).

NASSign=$<$integer$>$

is a required parameter that specifies the maximum expected number of assignments. It has to be greater than or equal to the actual number (default: 400).

RESEt

erases the restraints-dihedral database.

SCALe

specifies the overall weight factor $S$.