Vibrational trajectories for heavy quarkonia

Mukhopadhyay, Nimai C.; Zhang, L.

doi:10.1103/physrevd.44.2085

Cited by 7 publications

(16 citation statements)

References 20 publications

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“…However, like EOM-CC, it is built upon a solution for a reference SRCC state, while in Fock space, the P space consists of suitable determinants for the particular sector, like all 1h determinants for the [ [1,1], there is also benefit from increasing the P space. Importantly, FS-CC adds IV, and can do so for even incomplete P spaces [32]. In fact, one of the best ways to introduce triple excitations into EOM-CCSD, is to add selective elements missing that would arise from triples in a Fock space method, and that also ensures that the resulting equations are fully linked.…”

Section: Equation-of-motion CC Methodsmentioning

confidence: 99%

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To Multireference or not to Multireference: That is the Question?

Bartlett

2002

IJMS

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I present a personal viewpoint on multi-reference coupled-cluster theory, its pros and cons. I also suggest some criteria that should be satisfied by multi-reference CC, not the least of which is to develop a tool that will be (almost!) as easy to apply as today's powerful array of single reference coupled-cluster methods. Some approaches like the equation of motion CC method offers a multi-reference description of some target states, while being entirely single reference in execution. Perhaps it offers a model for further generalization to a wider array of multi-reference problems.

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Section: Equation-of-motion CC Methodsmentioning

confidence: 99%

“…Such an active space would be recommended for equivalent descriptions of the dissociation paths for this molecule, but, of course, is far beyond anything that could realistically be used. Some more restrictive incomplete model space choices can sometimes maintain extensivity [32], but CAS choices are severely limited [33].…”

Section: Nature Of the Problemmentioning

confidence: 99%

To Multireference or not to Multireference: That is the Question?

Bartlett

2002

IJMS

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“…[36] and applied in Ref. [37] for calculation of the ground-state and several vertical excitation energies of the molecule LiH. Being valid for an arbitrary incomplete MMS, this approach is considered in detail in Ref.…”

Section: Model Space Structure and Composition Of The Complete Systemmentioning

confidence: 99%

Multiconfigurational Green's function approach with quasidegenerate perturbation theory

Khrustov

Kostychev

2002

Int J of Quantum Chemistry

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ABSTRACT:The new approach to approximation of polarization propagator (PP) for electronic states of atoms and molecules with reference state wave function (RSWF) constructed on the base of a multidimensional model space is presented. This approach exploiting the apparatus of the quasidegenerate perturbation theory (QDPT) is realized in the zeroth QDPT order and through the first one. The original complete system of excitation operators introduced in the approach is consistent with the RSWF by the perturbation order. This factor in conjunction with the flexibility of the RSWF creates the capabilities of balanced accounting of correlation and quasidegeneracy effects at different locations of nuclei in a molecule and for all the states concerned. In this way, the transition characteristics in electronic shells of molecules in a wide area of nuclear geometry parameters may be appropriately evaluated.

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“…There is an earlier MRCC formulation by Mukhopadhyay and Mukherjee [26,27] which treats the orbital relaxations and the correlation relaxations on the same footing as in the ground state by invoking the Jeziorski and Monkhorst (JM) type of Ansatz for Ω V [10,11] advocated for their valence-specific MRCC (VS-MRCC) theories for state-energies per se. The modification consists in merely replacing the microscopic hamiltonian H by the dressed hamiltonian H = exp(−T )H exp(T ) − E gr , with E gr as the exact ground state energy.…”

Section: Normal Ordered Vs the New Ansatz For ω V And ωmentioning

confidence: 99%

“…(24) and (26) and is due to an 'extra' internal hole line in the diagrams of eqs. (24) and (26). All the S r operators in the modified CC equation for state energies are joined to the H vertex, and the S e operators joined from the left are also joined to the H vertex.…”

Section: Illustrative Applications To a Simple Open-shell Doubletmentioning

confidence: 99%

Use of a New Cluster Ansatz to Treat Strong Relaxation and Correlation Effects: A Direct Method for Energy Differences

Jana

Mahapatra

Mukherjee

2002

IJMS

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Abstract:We have presented in this paper a new cluster Ansatz for the wave operator for open-shell and/or quasidegenerate states, which takes care of strong relaxation and correlation effects in a compact and efficient manner. This Ansatz allows contraction among the various cluster operators via spectator orbitals, accompanied by suitable combinatorial factors. Since both the orbital and the correlation relaxations are treated on the same footing, it allows us to develop a very useful direct method for energy differences for open shell states relative to a closed-shell ground state, where the total charge for the two states may differ. We have discussed a new spin-free coupled cluster (CC) based direct method and illustrated its performance by evaluating electron affinity of a neutral doublet radical. We have also indicated how the scope of the theory can be extended to compute the state energies of simple open shell configurations as well. In that case, the CC equations terminate after the quartic power of cluster operators -exactly as in the closed-shell situation, which is not the case for the current methods.

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Vibrational trajectories for heavy quarkonia

Cited by 7 publications

References 20 publications

To Multireference or not to Multireference: That is the Question?

To Multireference or not to Multireference: That is the Question?

Multiconfigurational Green's function approach with quasidegenerate perturbation theory

Use of a New Cluster Ansatz to Treat Strong Relaxation and Correlation Effects: A Direct Method for Energy Differences

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