Symplectic shell-model calculations for 20Ne with horizontal configuration mixing

The symplectic shell model, which incorporates vertical (2n(h/2π)ω; n = 1, 2...) major shell configuration mixing as dictated by a quadrupole interaction, is augmented with horizontal (0(h/2π)ω) mixing induced by realistic single-particle energies and a monopole-pairing interaction. The excitation spectrum and B(E2) rates of the 20Ne ground band are accurately reproduced without the use of an effective charge. The degree of horizontal and vertical mixing is found to be on the order of 20% in the ground state and up to as much as 50% for the 8+ level. (orig.)