Multiple scattering approach to elastic low-energy electron collisions with the water dimer

Multiple scattering theory is applied to low-energy electron collisions with a complex target formed of two molecular scatterers. The total T-matrix is expressed in terms of the T-matrix for each isolated molecule. We apply the approach to elastic electron -(H2O)(2) collisions. Following the method developed in our previous work on crystalline ice (Caron et al 2007 Phys. Rev. A 76 032716), we impose a cut-off on the dipole outside the R-matrix sphere and an energy-dependent cut-off on the angular momentum components of the monomer T-matrix. An R-matrix calculation of electron - dimer collisions is performed in order to evaluate the accuracy of the multiple scattering approach. The agreement between the two calculations is very good.