This utility is the opposite number to formchk. It converts a formatted checkpoint file to a binary checkpoint file, in a format appropriate to the local computer system:
$ unfchk Formatted Checkpoint file? water Read formatted file water.fchk Write checkpoint file water.chk
The utility applies the extension .fch to the specified filename on Windows systems and the extensions .fchk on other computer systems.
The formatted checkpoint filename can also be given on the command line:
$ unfchk job222.chk Read formatted file "job222.fchk" Write checkpoint file "job222.chk" LenFI= 2580 MDV= 104857600 DoIMCk=T
Note that formatted checkpoint files can be used as a data exchange format between computer platforms. Use formchk on the originating computer and unfchk on the target computer to create a binary checkpoint file.
unfchk can also convert a matrix element file to a binary checkpoint file (see options)
In addition to formatted checkpoint files, unfchk can work with matrix element files and create binary checkpoint files containing their data.
Specifies the amount of memory to allocate to the utility. The options should specify an amount followed by units (the default unit is bytes). This option must precede all other options and command line arguments.
-matrix file1 file2
Reads (fortran unformatted) matrix element file file1.dat and writes checkpoint file file2.chk
-rawmatrix file1 file2
Reads (raw binary) matrix element file file1.dat and writes checkpoint file file2.chk
The following options specify the format of the matrix element file. They may be needed, depending on how the file was written by formchk, Gaussian, or whatever program created it.
Use this option when the Fortran unformatted matrix element file uses 8-byte integers.
Use this option when the Fortran unformatted matrix element file uses 4-byte integers.
Use this option when the Fortran unformatted matrix element file was written using 2-byte integers, for the two electron integral labels (and 4-bytes for most other integers).
Last updated on: 23 July 2019. [G16 Rev. C.01]