!IV.10. Widom insertion method

!This input shows how to run a Widom insertion calculation based on a
!pure water trajectory run earlier by CHARMM.

FILE methane
PRNT ECHO
TITL Calculate the chemical potential of Methane in Water
TITL using Widom cavity insertion method
HRDW VC32          ! 32-bit vector
SVVC MINI 10.0
SUVC MIGC 10.0      ! MI on the solute
PBCN RECT 15.5  15.5 15.5  !Rectangular PBC
TEMP 300   
NSLV 124 !no of solvent molecs in the CHARMM run
SVPT TIP4 TIP4 ! Solvent-solvent potential is TIP4P
SUPT CHRM      !Solute-solvent potential is CHARMM
FREE WIDO 2.6 64 64 64 2 5
SLTA SMPL MMC READ 5 5
 CT3     -0.13265   0.14073   0.03004  -0.36000    1  CSP3C1  
 HA       0.84914   0.15299   0.45527   0.09000    1  CSP3H11 
 HA      -0.35123  -0.84076  -0.33574   0.09000    1  CSP3H12 
 HA      -0.84914   0.40992   0.77775   0.09000    1  CSP3H13 
 HA      -0.18078   0.84077  -0.77776   0.09000    1  CSP3H14 
TRAJ CHRM RGFX  !Open trajectory in CHARMM format
SCAN TRAJ 1000 5 00 0 500 2 1  2 3 1
STOP 

!File needed for run:

!    * methane.hst: the CHARMM trajectory (DCD) file

!Files created by the run:

!    * methane.ckp: checkpoint files
!    * methane.pxc: analysis checkpoint file