Coupled cluster description of anharmonic molecular vibrations. Application to O3 and SO2

The performance of RI-MP2 based potential energy surfaces in a vibrational self-consistent field treatment

“…This approach, being chosen for many applications due to its foreseeable computational cost and the promising results, is commonly abbreviated as second order perturbation theory augmented (PT2) VSCF or correlation-corrected (CC)-VSCF [8,22,23]. For cases where mode-mode correlations become large and where a mode-separated reference state might not suffice, techniques such as vibrational configuration interac-A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 tion (VCI) [24,25,26,27], vibrational multi-configurational self-consistent field (VMCSCF) [28,29] or vibrational coupled cluster (VCC) [30,31,32] have been established, representing today's state-of-the-art in anharmonic computational spectroscopy.…”

Time Dependent Coupled Cluster Approach to Resonance Raman Excitation Profiles from General Anharmonic Surfaces

“…The coupled cluster approach to molecular vibrational energy levels consists of three steps [15]. In the first step a reference gaussian function is constructed variationally for the ground state:…”

“…In practice, this involves diagonalizing H eff in the n b (= Σn i ) ≠ 0 boson state manifold [15]. Since H eff is just a similarity transform of the original hamiltonian (via eq.…”

“…In addition, it has the desirable property of being size consistent. While most of the applications to date have been to the electronic structure problem, a few attempts have been made to apply it to the molecular vibrational problems as well [15,16]. The time dependent version of the coupled cluster method has been applied to the calculation of Franck-Condon spectra on harmonic [17] and coupled surfaces [18] with considerable success.…”

Selected Aspects Concerning the Efficient Calculation of Vibrational Spectra beyond the Harmonic Approximation

“…However, in the recent past impressive efforts have been undertaken in order to develop vibrational coupled-cluster methods, VCC, which in contrast to VCI theory show the advantage of size-consistency. 33,72,73 As the optimization of the VCC amplitudes for excited vibrational states may become rather problematic, the preferred route in this direction uses linear response calculations based on a VCC calculation for the energetically separated and low lying vibrational ground state (VCCLRT). [84][85][86] As several reviews are available on this topic, we will not reconsider all these approaches in detail here, but will focus on some specific aspects of vibrational structure calculations instead.…”