Third Cluster Coefficient for Square Well Discs

Sigurd Yves Larsen, Monique Lassaut, Alejandro Amaya-Tapia

W. Hoogeveen, John A. Tjon

William C. Elmore

C.A. Duque, Miguel Eduardo Mora-Ramos, C.A. Duque

Sigurd Yves Larsen

Using the method of binary collisions, the third virial coefficient of ${\mathrm{He}}^{4}$ at low temperatures is calculated for a potential consisting of an attractive square well and a repulsive core. The shape of this potential is chosen so as to optimize the fit of the second virial coefficient with experimental data. From a comparison of the results with the third virial data the existence of a three-body bound state is inferred. A binding energy of 0.26\ifmmode^\circ\else\textdegree\fi{}K, calculated from the potential, brings the adjusted results and the experimental data into agreement.

Zhi-En Lu, Guo Kang-Xian

The influence of electron-phonon interactions on third-harmonic generation in a square quantum well is investigated. The first- and third-harmonic generation coefficient is obtained by using compact-density-matrix approach and iterative method, and the numerical results are presented for a GaAs square quantum well. The results show that the third-harmonic generation coefficient is obviously enhanced after considering the influence of electron-phonon interactions.