Introduction

GVIB is a user friendly package for vibrational analysis. Given a molecular geometry, it will calculate vibrational frequencies and intensities using anharmonic internuclear potential. All the currently implemented methods use approximation based on Taylor expansion of the potential up to the 4th order.

What it can do?

Gvib can calculate

• - harmonic frequencies and corresponding IR,Raman and ROA intensities
• - eVSCF, gVSCF freqeuencies and IR,Raman and ROA intensities; VSCF+PT2 frequencies
• - harmonic+PT2 frequencies
• - harmonic+VCI frequencies and IR,Raman and ROA intensities

Installation

All the software is available under GPL and can be freely downloaded. To install the software, follow the usual procedure: unpack the tarball and run ./autogen.sh followed by ./configure --prefix=gvib_home and make install. You may also consider downloading tools for visualizing the molecular geometries and calculated spectra: the Molecule Maker gmm and Spectraview. To make Gvib tools available, add the following lines into your ~/.bash_profile (or run it in the terminal window before launching Gvib):

export GVIB_HOME=/path-to-gvib/gvib_home
. ${GVIB_HOME}/set-gvib-paths

Quick start

1. To model vibrational spectra of a molecule, start by optimizing its geometry. This step is required, because the program assumes that the first order derivatives of energy with respect to atom displacements are zero. Place the optimized geometry in a file (e.g. my_geometry.x) and run gvib by typing gvib --geometry my_geometry.x.
2. Gvib will run the Gaussian program for you to generate force constants and higher-order derivatives of the intermolecular potential. (Force constants can be calculated independently on multiple processors, so one may choose to take care of the displaced potentials himself and supply the results to gvib afterwards - see the action create-cc-inputs. This is of course the prefered way.)
3. Outputs of gvib are written into separate files under the locations specified in the configuration file. For the up-to-date state, run gvib with the -h option (see bellow).
4. The program is controlled by actions, which can be easily redefined and adjusted. For more on this, please read this README.

How does it work

The gvib package is a set of programs glued together by a perl script. The perl script takes care of reading configuration file and all the user-friendly things. The fortran and C programs beneath do the work.

The programs are independent and so it is easy to put your favourite program's calculation of potential in place of the default gaussian results, make isotopic substitutions etc. All the programs are controlled by enviroment variables which start with the prefix GVIB_. When you feel the urge to run (or debug) one of the gvib programs separately, just set the variables and run the program with no extra argument. When curious what variables has been set up, run gvib with the -d -l option (see bellow).

Documentation

• Gvib actions showed as a run-tree
• Index of default actions - reference for the gvib internals
• Default options and variables to gvib
• Supporting programs

• FAQ
• Ph.D. thesis (Try the PostScript version, if some characters are not displayed properly.)

Running gvib

Usage:	[Options] [config|project-directory]
Options:
	-a, --action <action1,action2,...>	Run the specified actions.
	-A, --avail	List available actions. (See also the -w option.)
	-c, --clean-log	Clean the log file before running.
	-C, --custom-settings <dir|config>	Show config variables not matching the default values.
	-d, --debug	Print debugging messages.
	-g, --geometry <file.x>	Geometry of the molecule.
	-h, --help	Get more help on the config file.
	-i, --ignore	Ignore GVIB_ enviroment variables.
	-l, --list	Do not run action, only list what would be done.
	-m, --module <Module>	User-supplied module, instead of the default "Actions".
	-o, --option-override <opt=value,..>	Override the given options.
	-r, --redo	Redo everything, even if the files are already done.
	-s, --silent	Print messages to the log file only.
	-w, --www-doc <directory>	Create www documentation in the specified directory.
	-?, --usage	This help message.

Examples

• Run gvib -a create-cc-inputs -g molecule.x to generate gaussian inputs displaced along cartesian coordinates. After all the gaussian jobs are calculated and placed back to the appropriate location, run gvib molecule/ to run all the anharmonic methods.

Authors

• Petr Daněček .
• Minor parts of code were taken from programs of Petr Bouř.
• Diagonalization routines TQLI and TRED were taken from Numerical Recipes.