Equation of motion coupled cluster theory calculations of the X-ray emission spectroscopy of water

The equation of motion coupled cluster theory including single and double excitations (EOM-CCSD) method is applied to study the X-ray emission spectroscopy of water. For the 1b1 orbital, a difference of about 0.7 eV is predicted between a tetrahedrally coordinated water molecule and a water molecule in which water molecules accepting hydrogen bonds are absent, and as a proton is dissociated emission from the 1b1 and 3a1 orbitals become closer in energy. The resonantly excited X-ray emission spectrum for the 4a1 orbital shows a red-shift in the bands and a reduction in intensity for the 3a1 band.