Molecule Types | <Prev Next> |

PGOPHER has can do two significant types of
calculations involving vibrations:

- Vibronic energy levels,
and the pattern of vibrational transitions associated with an
electronic transition. If an
*l*matrix is available for the states involved, then full multidimensional Franck-Condon factors can be calculated, but simpler empirical approaches can be taken if this is not available. - A force field analysis,
calculating vibrational frequencies,
*l*matrix, isotope shifts, rotational constants, centrifugal distortion constants and Coriolis coupling constants from the force constants and geometry of the molecule.

The force field calculation can feed directly
into calculating vibronic energy levels and transitions, or either
mode can be used in a stand alone manner. Either (or both)
calculation can be worked backwards to fit observed values to
molecular parameters. Both modes can use *ab initio*
calculations as a starting point, and even low quality *ab
initio* calculations can give a useful starting point for
analysis. A typical use case might involve an *ab initio*
calculation of the force field or other parameters, which is then
adjusted or refined to experimental observation or other criteria.

To start, work through the worked examples below.

- Introduction

- Making a basic data file for simulating vibrational structure
- Worked Example - The Photoelectron
Spectrum of H
_{2}O - Worked Example - Predicting the
Photoelectron Spectrum of H
_{2}O using ab initio Calculations - Importing l matrices
- Manual Import of the l matrix
- The l Matrix Window
- The Dushinsky Transformation Window
- Molecule Settings
- Electronic State Settings
- Vibrational Modes
- Nuclear Co-ordinates
- Perturbations
- Multidimensional Franck Condon factors
- Vibrational Mode Changes
- Sample Data Files

- Introduction
- Worked Example - Setting up a
simple force field analysis for H
_{2}O - Worked Example - Setting up a
combined force field analysis for H
_{2}O and D_{2}O - Worked Example - Refining an ab
initio force field for H
_{2}O - z Matrix
- Internal Coordinates
- Valence Coordinates
- Cartesian Coordinates
- Symmetry Coordinates
- Sample Data Files