“…To overcome this difficulty, we have suggested [18,19] to use the basis of the orthogonalized combinations of the spherical harmonics on the two-dimensional grid over θ and φ variables. It turned out that this idea was very efficient for the time-dependent Schrödinger equation with three [18][19][20][21][22][23][24] and four [1,4,25,26] nonseparable spatial variables. Especially productive it was for the quantitative description of the ultracold pair atomic collisions in confined geometry of harmonic traps (low-dimensional few-body systems) [1,2,4,9,[25][26][27].…”