Calculation of properties with the coupled‐cluster method

The cluster-expansion approach to the correlation problem, pioneered by Coester, Kummel, Cizek and Paldus, is extended to calculation of static and dynamic properties of many-fermion systems. Linear, inhomogeneous equations are obtained for properties of any order. A time-dependent formulation gives frequency-dependent properties, yielding excitation energies, transition probabilities, and (possibly) lifetimes reminiscent of Green's function methods.