We present results of microscopic calculations of the strength function [Formula Presented] and [Formula Presented]-particle excitation cross sections [Formula Presented] for the isoscalar giant dipole resonance (ISGDR). An accurate and general method to eliminate the contributions of spurious state mixing is presented and used in the calculations. Our results provide a resolution to the long standing problem that the nuclear matter incompressibility coefficient K deduced from [Formula Presented] data for the ISGDR is significantly smaller than that deduced from data for the isoscalar giant monopole resonance. 2002 The American Physical Society.
