Improvement of the coupled-cluster singles and doubles method via scaling same- and opposite-spin components of the double excitation correlation energy

Abstract

There has been much interest in cost-free improvements to second-order Møller-Plesset perturbation theory (MP2) via scaling the same- and opposite-spin components of the correlation energy (spin-component scaled MP2). By scaling the same- and opposite-spin components of the double excitation correlation energy from the coupled-cluster of single and double excitations (CCSD) method, similar improvements can be achieved. Optimized for a set of 48 reaction energies, scaling factors were determined to be 1.13 and 1.27 for the same- and opposite-spin components, respectively. Preliminary results suggest that the spin-component scaled CCSD (SCS-CCSD) method will outperform all MP2 type methods considered for describing intermolecular interactions. Potential energy curves computed with the SCS-CCSD method for the sandwich benzene dimer and methane dimer reproduce the benchmark CCSD(T) potential curves with errors of only a few hundredths of 1 kcal mol(-1) for the minima. The performance of the SCS-CCSD method suggests that it is a reliable, lower cost alternative to the CCSD(T) method.

Communication: Resolving the three-body contribution to the lattice energy of crystalline benzene: Benchmark results from coupled-cluster theory

“…54 The FNO CD-CCSD(T) computations were performed with a development version of the PSI4 program 55 using a recently developed, multi-core FNO DF/CD-CCSD(T) module. 47,53 We also obtained SCS-CCSD 56 and SCS(MI)-CCSD 57 values [as a byproduct of the CCSD(T) computations] to see how well these methods match CCSD(T) three-body energies, as recent work 58 suggests that they should be rather accurate for this purpose.…”

Chemical accuracy from quantum Monte Carlo for the benzene dimer

“…[30][31][32][33] Particularly the coupledcluster theory through perturbative triplets CCSD(T) which is often considered as the gold standard for chemical accuracy. 34,35 However, due to its substantial computational cost, scaling as N 7 where N is the number of electrons, more efficient methods for vdW systems are highly desirable.…”

Quantum Chemical Benchmark Energy and Geometry Database for Molecular Clusters and Complex Molecular Systems (www.begdb.com): A Users Manual and Examples

“…It is of special interest that a very wide variety of computational methods have been tested on a single set (S22), which allows for their direct comparison. The methods tested range from the pure DFT methods 9,13,14 through the combination of the DFT theory with empirical dispersion (DFT-D) 15-17 , hybrid and double hybrid DFT [18][19][20] , DFT with fully non-local correlation 21,22 , spin component scaled methods in MP2 [23][24][25] and CCSD 26 , r12 methods 27 , semiempirical methods 8 to quantum Monte Carlo 28 , symmetry adapted perturbation theory (SAPT) 29 and others [30][31][32][33] . Accurate interaction energies and geometries have also been useful as references in various applications 34 from biomolecules to nano-chemistry 34k,34l and, in the case of the peptides database, both for experimentalists 35 and theoreticians 36 .…”