Study of tetrehedral splittings in $E$ type states from polyad $N$=2.5 of XY$_4$ molecules (symmetry $T_d$)

The article considers the method of analytical description of one of the most difficult problem in the study of high symmetry quantum-mechanical objects, namely, of tetrahedral splittings; presents the results for determining in an analytical form tetrahedral splittings of vibrational states from polyad $N$=2.5 with symmetry $E$.