| Main Table of Contents | VERSION 4.6 |
| GROMACS homepage | Sat 19 Jan 2013 |
pdb2gmx automatically generates all angles, this means that the [angles] field is only useful for overriding .itp parameters.
pdb2gmx automatically generates one proper dihedral for every rotatable bond, preferably on heavy atoms. When the [dihedrals] field is used, no other dihedrals will be generated for the bonds corresponding to the specified dihedrals. It is possible to put more than one dihedral on a rotatable bond.
pdb2gmx sets the number exclusions to 3, which means that interactions between atoms connected by at most 3 bonds are excluded. Pair interactions are generated for all pairs of atoms which are seperated by 3 bonds (except pairs of hydrogens). When more interactions need to be excluded, or some pair interactions should not be generated, an [exclusions] field can be added, followed by pairs of atom names on seperate lines. All non-bonded and pair interactions between these atoms will be excluded.
A sample is included below.
[ bondedtypes ] ; mandatory
; bonds angles dihedrals impropers
1 1 1 2 ; mandatory
[ GLY ] ; mandatory
[ atoms ] ; mandatory
; name type charge chargegroup
N N -0.280 0
H H 0.280 0
CA CH2 0.000 1
C C 0.380 2
O O -0.380 2
[ bonds ] ; optional
;atom1 atom2 b0 kb
N H
N CA
CA C
C O
-C N
[ exclusions ] ; optional
;atom1 atom2
[ angles ] ; optional
;atom1 atom2 atom3 th0 cth
[ dihedrals ] ; optional
;atom1 atom2 atom3 atom4 phi0 cp mult
[ impropers ] ; optional
;atom1 atom2 atom3 atom4 q0 cq
N -C CA H
-C -CA N -O
[ ZN ]
[ atoms ]
ZN ZN 2.000 0