Coupled cluster-molecular mechanics response function

In this section we outline the coupled cluster-molecular mechanics response method, the CC/MM response method. Ref. [51] considers CC response functions for molecular systems in vacuum and for further details we refer to this article. The identification of response functions is closely connected to time-dependent perturbation theory [51,65,66,67,68,69,70], Our starting point is the quasienergy and we identify the response functions as simple derivatives of the quasienergy. For a molecular system in vacuum where Hqm is the vacuum Hamiltonian for the unperturbed molecule and V" is a time-dependent perturbation we have the following time-dependent Hamiltonian, H,... 

Kongsted, J., Osted, A., Mikkelsen, K. V., Christiansen, 0. (2003). Linear Response Functions for Coupled Cluster/Molecular Mechanics Including Polarization Interactions,/ Chem. Phys., 118,1620-1633. 

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