Approximation of scattering phases for Reid93 potential

For a single-channel nucleon-nucleon scattering, a well-known and convenient variable phase approach is considered, which is widely used for practical problems of atomic and nuclear physics. Approximation of the $pp$- and $np$- scattering phases obtained for the modern realistic phenomenological nucleon-nucleon potential Reid93 was carried out. The approximation function is used as a well-known formula for a parabolic-type quadratic function.