Direct analysis of nuclear distributional moments in zinc

Abstract

The direct-analysis formalism of Kurki-Suonio [e.g. Isr. J. Chem. (1977). 16, Nos. 2-3, 115-123, 132-136] is modified to apply to the calculation of nuclear distributional moments 〈xλyμzv〉, which are linear combinations of the multipole moments 〈rkylmp〉. They are integrated from the radical coefficients of the corresponding multipole terms through Gaussian and difference series procedures. An application to the thermal neutron diffraction structure factors of Merisalo & Larsen [Acta Cryst. (1977). A33, 351-354] on zinc indicates that the moment 〈x2〉 agrees with the anharmonic result of Merisalo & Larsen 〈z2〉 does not show discrepancy with the value based on harmonic assumption. The existence of the third-order component in the nuclear smearing function and, due to this, anharmonicity of thermal motion is well established, but the magnitude of 〈x3〉 is not accurately defined on the basis of the present data. The ratios of the fourth and second moments do not reveal deviation from harmonic thermal smearing.