Separation of a Slater determinant wave function with a neck structure into spatially localized subsystems

A method to separate a Slater determinant wave function with a two-center neck structure into spatially localized subsystems is proposed, and its potential applications are presented. An orthonormal set of spatially localized single-particle wave functions is obtained by diagonalizing the coordinate operator for the major axis of a necked system. Using the localized single-particle wave functions, the wave function of each subsystem is defined. Therefore, defined subsystem wave functions are used to obtain density distributions, mass centers, and energies of subsystems. The present method is applied to separations of Margenau--Brink cluster wave functions of $\alpha + \alpha$, $^{16}$O + $^{16}$O, and $\alpha + ^{16}$O into their subsystems, and also to separations of antisymmetrized molecular dynamics wave functions of $^{10}$Be into $\alpha$ + $^6$He subsystems. The method is simple and applicable to the separation of general Slater determinant wave functions that have neck structures into subsystem wave functions.