From 33003ffc85b1b8d36d0400b2363d5f5eefaab82b Mon Sep 17 00:00:00 2001
From: Rossen Apostolov <rossen@kth.se>
Date: Tue, 17 Jun 2014 10:51:09 +0200
Subject: [PATCH] Added information about dihedral restraints.

Fixes #1149.

Change-Id: Ifc6ab09d91116f3059addded11f8b0ed4f200545
---
 manual/forcefield.tex |  1 +
 manual/topology.tex   | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/manual/forcefield.tex b/manual/forcefield.tex
index ad6b965919..d99292b8c8 100644
--- a/manual/forcefield.tex
+++ b/manual/forcefield.tex
@@ -1155,6 +1155,7 @@ as in an improper dihedral (sec.~\ref{sec:imp}) but with a slightly
 modified potential. Using:
 \beq
 \phi' = \left(\phi-\phi_0\right) ~{\rm MOD}~ 2\pi
+\label{eqn:dphi}
 \eeq
 where $\phi_0$ is the reference angle, the potential is defined as:
 \beq
diff --git a/manual/topology.tex b/manual/topology.tex
index 35e4e821ce..87782be2f7 100644
--- a/manual/topology.tex
+++ b/manual/topology.tex
@@ -1365,6 +1365,11 @@ Urea         3
    2     1     1000       0    1000 ; Restrain to a line (Y-axis)
    3     1     1000       0       0 ; Restrain to a plane (Y-Z-plane)
 
+[ dihedral_restraints ]
+; ai   aj    ak    al  type  label  phi  dphi  kfac  power
+    3    6     1    2     1      1  180     0     1      2
+    1    4     3    5     1      1  180     0     1      2
+
 ; Include TIP3P water topology
 #include "amber99/tip3p.itp"
 
@@ -1474,6 +1479,19 @@ to reference positions (\ssecref{positionrestraint}).
 The reference positions are read from a 
 separate coordinate file by {\tt \normindex{grompp}}.
 
+
+{\bf {\tt [~dihedral_restraints~]} :} restrain selected dihedrals to a reference value.
+The implementation of dihedral restraints is described in section \ssecref{dihedralrestraint} of the manual.
+The parameters specified in the [dihedral_restraints] directive are as follows:
+\begin{itemize}
+\item {\tt type} has only one possible value which is 1
+\item {\tt label} is unused and has been removed from the code.
+\item {\tt phi} is the value of $\phi_0$ in \eqnref{dphi} and \eqnref{dihre} of the manual.
+\item {\tt dphi} is the value of $\Delta\phi$ in \eqnref{dihre} of the manual.
+\item {\tt kfac} is analogous to {\tt fac} in the implementation of distance restraints. It is the factor by which the force constant is multiplied. By doing so, different restraints can be maintained with different force constants.
+\item {\tt power} is unused and has been removed from the code.
+\end{itemize}
+
 {\bf {\tt \#include "tip3p.itp"} :} includes a topology file that was already
 constructed (see section~\ssecref{molitp}).
 
-- 
2.22.0