* This is a reduced version of the CHARMM22 parameter file for 
* a nanotube simulation in water
*

BONDS
!V(bond) = Kb(b - b0)**2
!
!atom type Kb          b0
CA   CA    305.000     1.3750
HT   HT      0.000     1.5139
OT   HT    450.000     0.9572


ANGLES
!V(angle) = Ktheta(Theta - Theta0)**2
!V(Urey-Bradley) = Kub(S - S0)**2
!
!atom types     Ktheta    Theta0   Kub     S0
CA   CA   CA    40.000    120.00   35.00   2.41620
HT   OT   HT     55.000   104.5200 

DIHEDRALS
!V(dihedral) = Kchi(1 + cos(n(chi) - delta))
!
!atom types             Kchi    n   delta
CA   CA   CA   CA       3.1000  2   180.00


NONBONDED nbxmod  5 atom cdiel shift vatom vdistance vswitch -
cutnb 14.0 ctofnb 12.0 ctonnb 10.0 eps 1.0 e14fac 1.0 wmin 1.5 
!V(Lennard-Jones) = Eps,i,j[(Rmin,i,j/ri,j)**12 - 2(Rmin,i,j/ri,j)**6]
!
!atom  ignored    epsilon      Rmin/2
CA     0.000000  -0.070000     1.992400
HT     0.000000  -0.046000     0.224500
OT     0.000000  -0.152100     1.768200

HBOND CUTHB 0.5

END