where is the one-electron exchange operator,
are the one-electron wavefunction being acted upon by the Exchange operator as functions of the positions of electron 1 and electron 2,
are the one-electron wavefunction of the j-th electron as functions of the positions of electron 1 and electron 2,
is the distance between electrons 1 and 2.
In Quantum Physics the Exchange Operator can be thought of as a Hermitian operator which swaps the labels on any two identical particles.