THEORY QUANTUM CRYSTALS

A tutorial review is given of the theory of crystals with large-amplitude, highly anharmonic vibrational motion. Applications are discussed to the lighter solid rare gases, particularly helium, as well as to the ferroelectric-lattice structural transformation. The single-particle and the collective pictures of the starting coordinate basis set are developed and compared. Formulas are presented for the phonon damping in the collective picture. A survey is outlined of Jastrow function treatments of short-range correlation due to hard-core interatomic repulsion in solid helium. © 1969, American Association of Physics Teachers. All rights reserved.