The entropy of two-dimensional ice has been found by the transfer-matrix method. $\mathrm{Entropy}=Mk\ln W$, with $M=\mathrm{No}.\mathrm{of}\mathrm{molecules}$ and $W={\left(\frac{4}{3}\right)}^{\frac{3}{2}}$.

The relationship between the dispersion-theory and perturbation-theory approach to scattering in dilute magnetic alloys is established.

A phonon Raman process due to a combination of the direct spin-lattice coupling and the cubic anharmonic lattice forces is shown to be important in nuclear quadrupole relaxation in alkali-halide crystals.

Assuming that the Regge trajectories ${\alpha }_{10}\mathrm{}\left(0\right)\mathrm{}$, ${\alpha }_{{10}^{*}}\mathrm{}\left(0\right)\mathrm{}$, and ${\alpha }_{27}\mathrm{}\left(0\right)\mathrm{}$ are less than 0, we derive sum rules for photoproduction. Comparison with the experiment is given.

Applying shear to the magnetic field confining a thermally ionized potassium plasma reduces the escape rate by as much as a factor of 30. This effect is accompanied by both a reduction and a localization of the low-frequency oscillations.

Cardona and Greenaway's identifications of the ${E_0}^{\prime }$, ${E_1}^{\prime }$, and ${E_1}^{\prime }+{\Delta }_1$ peaks in the optical reflectivity spectrum of CdTe are contradicted by deductions drawn from photoemission measurements. New identifications of these peaks are proposed on the basis of these photoemission measurements and the results of empirically adjusted orthogonalized-plane-wave energy band calculations. Our theoretical band model for CdTe differs in some important respects from that derived by Cohen and Bergstresser using the empirical pseudopotential method.

The expansion of a crystal potential in terms of a set of three-dimensional polynomials orthogonalized with respect to the weight function $f^2({\overrightarrow{\mathrm{r}}}_1, {\overrightarrow{\mathrm{r}}}_2, \cdots ,{\overrightarrow{\mathrm{r}}}_N)\exp \left[\right({\overrightarrow{\mathrm{r}}}_i-{\overrightarrow{\mathrm{R}}}_i\left)·{\mathrm{G}}_{\mathrm{ij}}·\right({\overrightarrow{\mathrm{r}}}_j-{\overrightarrow{\mathrm{R}}}_j\left)\right]$ is shown to be a logical generalization of the previously introduced self-consistent harmonic approximation which is particularly appropriate for highly anharmonic systems. Explicit expressions for the calculation of the ground-state energy and phonon spectrum of a crystal at 0°K are given and certain numerical results for solid ${\mathrm{He}}^3$ at 0°K are presented.