Vibrational spectra of molecules in the Hartree–Fock dielectric screening approach

✍ Scribed by P. E. Van Camp; V. E. Van Doren; J. T. Devreese

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 243 KB
• Volume: 18
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/qua.560180144

✦ Synopsis

Abstract

Traditionally, the calculation of the vibrational spectra of molecules involves at one point or another a numerical differentiation procedure. Such a method has some serious drawbacks both in efficiency and in accuracy. In this paper, an alternative method based on linear response theory is presented. The second derivative of the ground‐state energy is expressed in terms of the electron density response matrix by means of perturbation theory. The unperturbed wave functions are obtained from the Hartree–Fock equation. First‐order perturbation theory applied to this equation leads to the Hartree–Fock linear response. As an illustration of this method the vibrational frequency of a H~2~ molecule is calculated. The result is 1.348 × 10^14^ Hz as compared to the experimental value of 1.319 × 10^14^ Hz. This method is also applicable in the calculation of the phonon dispersion curves of solids.