Purpose: Calculates the state populations from a psi file.
 Usage:   stpoppsi [-i -f -d -o -r -n -skip -step -tcut -w  -ver -h -?]

Options  : 
 -i DIR  : data is stored in directory DIR
 -f FILE : the PSI is read from FILE rather than from ./psi
           The string FILE may be a relative or a full path-name.
 -d FILE : the DVR is read from FILE rather than from ./dvr
           The string FILE may be a relative or a full path-name.
 -o FILE : The ouput is written to file FILE rather than to ./stpoppsi
           The string FILE may be a relative or a full path-name.
  If FILE=no, i.e. -o no, no output file will be written.
 -r      : The PSI is read from restart file rather than from ./psi
 -n num  : only the first num WFs are read  from psi-file.
 -skip m : the first m WFs are skipped.
 -step step : Compute the population only every step-th WF.
 -tcut tcut : Compute the population only at time tcut.
 -w      : Overwrite the output-file stpoppsi.
 -ver    : Version information about the program 
 -h      : Print this help text. 
 -?      : Print this help text.