CoupledClusterVerfahren
Coupled cluster theory is a family of ab initio quantum chemical methods used to compute the electronic structure of molecules. It is based on an exponential ansatz for the electronic wavefunction, which provides a balanced description of dynamic correlation and yields size-extensive energies and good accuracy for a wide range of systems.
In the standard single-reference formulation, the wavefunction is written as Psi = exp(T) Phi0, where Phi0 is
Extensions include CC with triples and quadruples: CCSDT, CCSDTQ; the equation-of-motion CC (EOM-CC) family for excited
However, CC methods assume a predominantly single-reference character and can fail for systems with strong static