Lane, Joseph R.2013-01-232013-01-232013-01-082013Lane, J. R. (2013). CCSDTQ optimized geometry of water dimer. Journal of Chemical Theory and Computation, 9(1), 316-323.1549-9618https://hdl.handle.net/10289/7098The equilibrium geometry of the lowest energy structure of water dimer [(H₂O)₂] has been investigated using coupled cluster theory. A hierarchy of conventional coupled cluster methods is utilized up to singles doubles triples and quadruples excitations (CCSDTQ). The geometry of (H₂O)₂ is also optimized using the explicitly correlated coupled cluster singles doubles and perturbative triples [CCSD(T)-F12b] method. Overall, we find that the effect of including excitations beyond CCSD(T) is smaller than inclusion of core-valence correlation and comparable to scalar-relativistic and adiabatic effects.enJournal Article10.1021/ct300832f