Renormalized coupled-cluster calculations of reactive potential energy surfaces: A comparison of the CCSD(T), renormalized CCSD(T), and full configuration interaction results for the collinear BeFH system

Abstract

Articles you may be interested inSymmetric and asymmetric triple excitation corrections for the orbital-optimized coupled-cluster doubles method: Improving upon CCSD(T) and CCSD(T)Λ: Preliminary application Active-space symmetry-adapted-cluster configuration-interaction and equation-of-motion coupled-cluster methods for high accuracy calculations of potential energy surfaces of radicals The X Σ g + 1 , B Δ g 1 , and B ′ Σ g + 1 states of C 2 : A comparison of renormalized coupled-cluster and multireference methods with full configuration interaction benchmarksThe recently proposed renormalized ͑R͒ and completely renormalized ͑CR͒ coupled-cluster singles, doubles, and noniterative triples ͑CCSD͑T͒͒ methods have been used to calculate the ground-state potential energy surface ͑PES͒ for the collinear BeFH system corresponding to the BeϩHF →BeFϩH reaction. It has been demonstrated that the ground-state PES obtained in the CR-CCSD͑T͒ calculations is in perfect agreement with the exact PES obtained in the full configuration interaction calculations, whereas the PES resulting from the standard CCSD͑T͒ calculations is qualitatively incorrect.

New Alternatives for Accurate Electronic Structure Calculations of Potential Energy Surfaces Involving Bond Breaking

“…The name "quasi-variational", in reference to all MMCC methods based on eqs (28) or (29), originates from the fact that by inserting the wave function jyQVMMCc\ eq (27), into eq (16) or into the equivalent MMCC functional, eq (20), and oy assuming that Σ = f^9 we obtain the expectation value of the Hamiltonian with the CC wave functioned |φ), which is an upper bound to the exact ground-state energy. Indeed, by replacing |Ψ 0 ) in eqs (16) and (20) …”

“…The CR-CCSD[T], CR-CCSD(T), and CR-CCSD(TQ) methods remove the failing of the CCSD[T], CCSD(T), and CCSD(TQ f ) approaches at larger internuclear separations and often provide an excellent description of PESs involving single and double bond dissociation (P, 13,15,[17][18][19][20][21]111). However, the CR-CCSD(T) and CR-CCSD(TQ) results for triple bond breaking and for certain types of double bond breaking (e.g., in C 2 ) are somewhat less accurate (14,18,21).…”

“…The original derivation of eq (16), presented in ref 9, has been based on the analysis of the mathematical relationships between multiple solutions of nonlinear equations representing different CC approximations (CCSD, CCSDT, etc.). An elementary derivation of eq (16), based on applying the resolution of identity to an asymmetric energy expression, (20) defining the so-called MMCC functional, has been given in Appendix A of ref 13 (cf., also, refs 27, 106).…”

“…It has been demonstrated in several benchmark calculations that the CR-CCSD(T) (completely renormalized CCSD(T)) and CR-CCSD(TQ) (completely renormalized CCSD(TQ)) methods provide an excellent description of entire PESs involving single and double bond dissociation (9, 13, 15, 17-19, 21, 111), highly-excited vibrational term values near dissociation (17,18,21,111), and entire PESs for exchange chemical reactions of the general type: closed shell + closed shell doublet + doublet (20,21). However, the CR-CCSD(T) and CR-CCSD(TQ) results for triple bond breaking (e.g., in N 2 ) and for certain types of double bond breaking (e.g., in C 2 ) are somewhat less impressive (14,18,21).…”

Study of energetics of end‐on and side‐on peroxide coordination in ligated Cu2O2 models with State‐Specific Equation of Motion Coupled Cluster Method

“…Despite the widespread use of DFT method in studying transition metal compounds, its applicability is not well established and cases where it fails are not unusual. CR-CC [25][26][27][28] has been successfully applied to many systems [29][30][31][32][33][34][35][36][37], but essentially being a single reference method, it is not transparent to what extent it can be used for multireference systems. Multireference configuration interaction (MRCI), multireference perturbation theory (MRPT, especially CASPT2 [38,39]) are well established ab initio methods.…”