The notion of spatial-energy parameter (P-parameter) is introduced based on the modified Lagrangian equation for relative motion of two interacting material points, which is a complex characteristic of important atomic values. Wave properties of P-parameter are found, its wave equation having a formal analogy with the equation of Ψ-function is given. In the systems in which the interactions proceed along the potential gradient (positive performance) the resulting potential energy is found based on the principle of adding reciprocals of the corresponding energies of subsystems. Some correlations of P-parameter values with Lagrangian and Hamiltonian functions are obtained.