Minimizing a structure using OPTIM and CHARMM

To optimize a geometry you need an input.crd file, as well as odata:

1. input.crd -- file with coordinates in CHARMM'S CARD format

2. odata -- file with OPTIM keywords specifying method of minimization, convergence criterion, etc. e.g.:

  BFGSMIN 1.0D-6
  BFGSSTEPS 10000
  UPDATES 1000
  MAXERISE 1.0D-4
  ENDHESS (optional, if you want to know the log product of positive Hessian eigenvalues)
  CHARMMTYPE toph19_eef1_perm.inp param19_eef1_perm.inp
  CHARMM
  ... the usual charmm stuff, but making sure that input.crd is the file from which the coordinates are read in, for example:
  OPEN UNIT 20 NAME input.crd READ CARD
  ...