Four- and 8-reference state-specific Brillouin-Wigner coupled-cluster method: Study of the singlet oxygen

We developed and implemented the state-specific Brillouin–Wigner coupled-cluster theory restricted to single and double excitations (BWCCSD) method for a general number of closed- and open-shell reference configurations. The method (together with the previously suggested a posteriori size-extensivity correction) is applied to the calculation of oxygen molecule in the X3Σ, a1Δg, and b1Σ states, and results of this multireference treatment are compared with those obtained by the DIP STEOMCCSD and multireference (MR)-CISD methods and with experimental spectroscopic data. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002

[1]  C. Bauschlicher,et al.  Theoretical study of the low-lying bound states of O2 , 1991 .

[2]  S. Wilson,et al.  On the use of Brillouin-Wigner perturbation theory for many-body systems , 2000 .

[3]  I. Hubač,et al.  Comparison of the Brillouin-Wigner Coupled Cluster Theory with the Standard Coupled Cluster Theory. Cancellation of Disconnected Terms in the Brillouin-Wigner Coupled Cluster Theory , 1997 .

[4]  Rodney J. Bartlett,et al.  Similarity transformed equation-of-motion coupled-cluster theory: Details, examples, and comparisons , 1997 .

[5]  V. Minaeva,et al.  MCSCF response calculations of the excited states properties of the O2 molecule and a part of its spectrum , 2001 .

[6]  S. J. Cole,et al.  Single‐Reference Coupled‐Cluster Calculations of the Triplet Ground‐State O2 Dissociation Potential , 1991 .

[7]  H. Monkhorst,et al.  Coupled-cluster method for multideterminantal reference states , 1981 .

[8]  J. Pittner,et al.  Four-Reference State-Specific Brillouin-Wigner Coupled-Cluster Method: Study of the IBr Molecule , 2001 .

[9]  Ivan Hubač,et al.  Size-extensivity correction for the state-specific multireference Brillouin–Wigner coupled-cluster theory , 2000 .

[10]  Ivan Hubač,et al.  Multireference Brillouin-Wigner Coupled-Cluster Theory. Single-root approach. , 1998 .

[11]  J. L. Dunham.  The Energy Levels of a Rotating Vibrator , 1932 .

[12]  Karol Kowalski,et al.  The method of moments of coupled-cluster equations and the renormalized CCSD[T], CCSD(T), CCSD(TQ), and CCSDT(Q) approaches , 2000 .

[13]  J. Pittner,et al.  Multireference coupled-cluster calculations on the energy of activation in the automerization of cyclobutadiene: Assessment of the state-specific multireference Brillouin–Wigner theory , 2000 .

[14]  Marcel Nooijen,et al.  Many‐body similarity transformations generated by normal ordered exponential excitation operators , 1996 .

[15]  J. Pittner,et al.  State-Specific Brillouin−Wigner Multireference Coupled Cluster Study of the Singlet−Triplet Separation in the Tetramethyleneethane Diradical , 2001 .

[16]  Petr Nachtigall,et al.  Assessment of the single-root multireference Brillouin–Wigner coupled- cluster method: Test calculations on CH2, SiH2, and twisted ethylene , 1999 .

[17]  Rodney J. Bartlett,et al.  A new method for excited states: Similarity transformed equation-of-motion coupled-cluster theory , 1997 .

[18]  Donald C. Comeau,et al.  The equation-of-motion coupled-cluster method. Applications to open- and closed-shell reference states , 1993 .

[19]  J. Pittner,et al.  State-specific Brillouin–Wigner multireference coupled cluster study of the F2 molecule: assessment of the a posteriori size-extensivity correction , 2001 .

[20]  I. Hubač.  Size-Extensive Brillouin-Wigner Perturbation Theory. Size-Extensive Brillouin-Wigner Coupled Cluster Theory , 1996 .