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# Accession Number:

## AD0701043

# Title:

## LATTICE DYNAMICS OF CdS. 1. NEAREST NEIGHBOR APPROXIMATION,

# Descriptive Note:

# Corporate Author:

## DAYTON UNIV OHIO DEPT OF PHYSICS

# Report Date:

## 1969-11-01

# Pagination or Media Count:

##
58.0

# Abstract:

## The report presents the first part of a study on the lattice dynamics of CdS and assumes only nearest-neighbor interaction between the ions. The structure of cadmium sulfide in its wurtzite form is discussed. A short discussion of the first Brillouin zone of the crystal is given. The equations of motion of the lattice are derived assuming a one parameter nearest neighbor type of potential. The usual form for displacements in a periodic potential is assumed. As there are four atoms in the basis, there are four independent vector displacements involved. The dynamical matrix obtained is diagonalized yielding the eigenvalues and eigenvectors of the matrix. The eigenvalues are the normal mode frequencies squared of the photons. The eigenvectors are closely related to the normal modes of the lattice. This relationship is demonstrated explicitly for the wave vectors at the gamma point of the Brillouin zone. Dispersion curves are given indicating the phonon energies predicted by this model for fourteen symmetry points of the Brillouin zone. It is found that this model gives only qualitative agreement with experiment. Author

# Distribution Statement:

## APPROVED FOR PUBLIC RELEASE

#