Neutron-proton pairing, Coulomb effects and shape coexistence in odd-odd N= Z 46V

High-spin states up to the f7/2-shell band termination at Jπ = 15+ have been observed in the odd-odd N = Z = 23 nucleus V. A revised and significantly extended level scheme contains two distinct structures corresponding to spherical and prolate shapes. A band exhibiting rotational-like behaviour in the latter structure has excellent correspondence with the yrast sequence in Ti and is therefore assumed to be a T = 1 configuration. The difference between excited analogue states in the two nuclei is interpreted as a Coulomb effect and its variation with spin associated with np-pair alignment effects in V. Shell-model calculations have been performed and are in good quantitative agreement with experimental level energies. The competition between T = 1 and T = 0 structures is also reproduced. © 1999 Elsevier Science B.V. All rights reserved.