Application of a grid numerical method to calculate state-selective cross sections for electron capture in Be4+ + H(1s) collisions

Charge-transfer n partial cross sections have been calculated for collisions of Be4+ with H(1s) by means of a versatile lattice method that is applicable in a wide energy range (between 1 and 500 keV/u). The cross sections, which include up to the high-lying n = 8 level, are compared to existing semiclassical calculations in order to quantify the accuracy of the results. The reliability of the lattice method at high impact energies is confirmed by comparison with classical trajectory Monte Carlo calculations. It is found that the n partial cross sections larger than 10(-18) cm(2), calculated using the lattice method, agree with differences smaller than 15% with those from the method considered the most accurate at each energy. The calculation yields as well accurate total electron capture cross sections, which are studied in detail at E = 100 keV/u to obtain a converged value.