Masses from inhomogeneous partial difference equations

Abstract

Procedures are described for obtaining mass predictions from the solutions of inhomogeneous partial difference equations. The inhomogeneous contributions result from the variation with nucleon number and neutron excess of the effective neutron-proton interaction. A simple liquid-drop-model expression has been used for these contributions to obtain the present predictions. The most general solutions of the difference equation have been subjected to a [chi]2-minimization procedure (boundary condition) based on the new atomic mass adjustment of Wapstra and Bos. The resulting solution can be viewed as a many-parameter mass equation with about 220 parameters. About 5000 mass values have been calculated for nuclei with A >= 65. The standard deviation between calculated and experimental mass-excess values is [sigma]m = 289 keV.