*>>>> CHARMM22 Parameter File for Water <<<<<<<<<<<<<<<<
*>>>>>>>>>>>>>>>>>>>>>>> Sept. 2004 <<<<<<<<<<<<<<<<<<<<
*>>>>>>>>>>>>>> Prepared by T. I. Morrow <<<<<<<<<<<<<<<

! REMARKS
!
BONDS
!
!V(bond) = Kb(b - b0)**2
!
!Kb: kcal/mole/A**2
!b0: A
!
!atom type Kb          b0
!
SPCH SPCO   545.00      1.000   ! SPC/E rigid water
HT   OT     545.00      1.000   ! Protomol example water
!SPCH SPCH     0.00      1.630   !

ANGLES
!
!V(angle) = Ktheta(Theta - Theta0)**2
!
!V(Urey-Bradley) = Kub(S - S0)**2
!
!Ktheta: kcal/mole/rad**2
!Theta0: degrees
!Kub: kcal/mole/A**2 (Urey-Bradley)
!S0: A
!
!atom types     Ktheta    Theta0   Kub     S0
!
!-- Water models
SPCH SPCO SPCH      55.0    109.47 ! SPC/E rigid water
HT   OT   HT        55.0    109.47 ! protomol example water

DIHEDRALS
!
!V(dihedral) = Kchi(1 + cos(n(chi) - delta))
!
!Kchi: kcal/mole
!n: multiplicity
!delta: degrees
!
!atom types             Kchi    n   delta

IMPROPER
!
!V(improper) = Kpsi(psi - psi0)**2
!
!Kpsi: kcal/mole/rad**2
!psi0: degrees
!note that the second column of numbers (0) is ignored
!
!atom types           Kpsi                   psi0

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 
                !adm jr., 5/08/91, suggested cutoff scheme
!
!V(Lennard-Jones) = Eps,i,j[(Rmin,i,j/ri,j)**12 - 2(Rmin,i,j/ri,j)**6]
!
!epsilon: kcal/mole, Eps,i,j = sqrt(eps,i * eps,j)
!Rmin/2: A, Rmin,i,j = Rmin/2,i + Rmin/2,j
!
!atom  ignored    epsilon      Rmin/2   ignored   eps,1-4       Rmin/2,1-4
!
!-- Water
SPCO   0.0       -0.15525      1.774 ! SPC/E Oxygen
SPCH   0.0       -0.00000      1.000 ! SPC/E Hydrogen
OT     0.0       -0.15525      1.774 ! protomol example water
HT     0.0       -0.0000       1.000 ! protomol example water

HBOND CUTHB 0.5  ! If you want to do hbond analysis (only), then use
                 ! READ PARAM APPEND CARD
                 ! to append hbond parameters from the file: par_hbond.inp

END