Physical Properties of an Off-Center Impurity in the Tunneling Approximation. I. Statics

Low Temperature Heat Capacity and Thermal Expansion of KCI Containing a Low Concentration of Li+

“…Within experimental error, the results of the combined measurements are consistent with deductions from a phenomenological model (Gomez et al 1967) in which Li+ ions are displaced about 0·05 nm from the substitutional cationic sites in one of eight equivalent <Ill) directions. The resulting dipole can tunnel quantum-mechanically 'around' the simple cube formed by the eight sites and can contribute a Schottky term to the free energy of the crystal.…”

“…Within experimental error both the excess heat capacity and the excess thermal expansion attributed to the Li+ -vacancy dipoles are described well by the phenomenological, four-level model of Gomez et al (1967) where 27T-li is Planck's constant, w is the fundamental oscillator frequency, and 1] = mwx 2 /-li is the ratio of the barrier height to the zero point energy of the oscillator; here m is the mass of the Li+ ion and 2x is the separation between the oscillator centres.…”

Impurity-Induced Far-Infrared Absorption in KBr and KCl

“…Subsequent calculations using three dimensional models by Das (1967), Wilson et al (1967) and by Gomez, Bowen and Krumhansl (1967) The experimental curve is shown in Fig. (29).…”

“…em In a recent paper by Kirby, Hughes and Sievers (1970) - 1 new absorption measurements on the 40 em band were presented and compared with the tunneling model of Gomez, Bowen and Krumhansl (1967).…”

Static and dynamic properties of systems with multipole interactions and internal dynamic structure

“…Dilute systems of these impurities were studied at Cornell experimentally by Pohl, Sack, Sievers, Silsbee and co-workers (a review article is Narayanamurti and Pohl, 1970), and theoretically by Krumhansl and Gomez (Gomez et al, 1967). The individual particles have (in common with the harmonic oscillator or free rotor) a singlet ground state and triplet excited state, plus higher states.…”