Momentum density of vanadium: A reconstruction from two-dimensional positron-annihilation data

The momentum distribution, {ρ}(p), in vanadium has been reconstructed from two-dimensional (2D) angular correlation of positron-annihilation radiation (ACPAR) data sets nR(pₓ,py). Reconstruction has been performed by using an expansion in terms of cubic harmonics on experimental as well as theoretical data sets nR(pₓ,py) for four orientations in V. The effect of statistical errors propagated during the reconstruction is also estimated. The results for {ρ}(p) reconstructed from experiment are compared with those from theory by examining radial plots of the momentum distribution, 2D surfaces and their contour plots in various (pₓ,py) planes. A satisfactory agreement is observed in the general structure shown by the experimental and theoretical distributions and the observed structure is analyzed in terms of contributions from different sheets of Fermi surface (FS) of V. The ratio of NP{}/NH{} of the semiaxes of the N-centered ellipsoidal hole FS sheet in V has been determined to be 1.36 from 2D ACPAR experiment, and this value agrees well with the ratio found by other experimental techniques. Present results show that a wealth of information about {ρ}(p) can be reconstructed from nR(pₓ,py) measured for a limited number of orientations.