Determining Vibrational Frequencies and Intensities via Finite Displacements for CI and CC Computations

In order to extract vibrational frequencies and intensities from our correlated methods, it is necessary to employ the technique of finite displacements. Questions may be directed to the author, Jeff Stephens.

 
• Preprocessing
• Generate Displacements
• Check Equilbrium Geometry in Lower Symmetries
• 4. Calculating Derivatives and Dipole Moments
• Create Composite file11 and file28.
• Transform the Gradients in Cartesian Coordinates to Internal Coordinates.
• Calculate Dipole Moment First Derivatives in Internal Coordinates (for Intensities)
• Transforming Dipole Moment Derivatives from Internals to Cartesians
• Generate the Second Derivatives of the Energy in Internal Coordinates.
• Transforming the Second Derivatives of the Energy into Cartesian and Calculation of the Frequencies and Intensities
• Obtaining Force Constants (Optional)
• Finit2freq: An easier method? (Optional)
• Isotopic Substitution (Optional)