To obtain the perturbated matrics elements of the non-harmonic oscillator by the two properties of the coherent state-non-orthogonality and supercompleteness,furthermore,to obtain the second-order approximated value of the energy when the perturbation term such as λq m acted on it.
We investigated the coherent states of nonconservative harmonic oscillator with a singular perturbation. The invariant operator represented in terms of lowering and raising operators. We confirmed that if the difference between two eigenvalues, α and β, of coherent states is much larger than unity, the states |α> and |β> are approximately orthogonal to each another. We calculated the expectation values of various quantities such as invariant operator, Hamiltonian and mechanical energy in coherent state. The mechanical energy of the system described by the Kanai–Caldirola Hamiltonian decreased exponentially depending on γ as time goes by in coherent state.