Electron and positron impact differential cross sections for the (e,2e) process on water molecule

We present a theoretical study for electron and positron-impact ionization of water molecule by using the three-body formalism of distorted-wave approximation. In this approximation, the final state contains one-Coulomb, two-Coulomb, and three-Coulomb distortion due to pairwise Coulombic interactions, respectively. In the entrance channel, the initial state is a product of two wavefunctions: the first one for the incident electron/positron described by a Coulomb wave and the second one for the ten bound electrons. The molecular wavefunction for these bound electrons of $H_{2}O$ are described by the linear combination of atomic orbitals. We investigate the angular distribution of the triple differential cross section (TDCS) for single ionization of the outer orbitals $1b_1,3a_1,1b_2$, and $2a_1$. The structure with two peaks around the binary and recoil region are clearly observed for $1b_1$, $3a_1$, and $1b_2$ orbitals. At the same time, a single peak in the binary region with no recoil peak is found for the $2a_1$ orbital. The present TDCS results are compared with available experimental and theoretical findings. Fair agreement regarding the structure of angular profile of the TDCS is observed for all orbitals except $2a_1$. Finally, an enhanced TDCS have been found for positron impact compared to the electron impact.