title: Construction of a Spin-Component Scaled Dual-Hybrid Random Phase Approximation.
abstract: Recently, we have constructed a dual-hybrid direct random phase approximation method, called dRPA75, and demonstrated its good performance on reaction energies, barrier heights, and noncovalent interactions of main-group elements. However, this method has also shown significant but quite systematic errors in the computed atomization energies. In this paper, we suggest a constrained spin-component scaling formalism for the dRPA75 method (SCS-dRPA75) in order to overcome the large error in the computed atomization energies, preserving the good performance of this method on spin-unpolarized systems at the same time. The SCS-dRPA75 method with the aug-cc-pVTZ basis set results in an average error lower than 1.5 kcal mol-1for the entire n-homodesmotic hierarchy of hydrocarbon reactions (RC0-RC5 test sets). The overall performance of this method is better than the related direct random phase approximation-based double-hybrid PWRB95 method on open-shell systems of main-group elements (from the GMTKN30 database) and comparable to the best O(N4)-scaling opposite-spin second-order perturbation theory-based double-hybrid methods like PWPB95-D3 and to the O(N5)-scaling RPAX2@PBEx method, which also includes exchange interactions. Furthermore, it gives well-balanced performance on many types of barrier heights similarly to the best O(N5)-scaling second-order perturbation theory-based or spin-component scaled second-order perturbation theory-based double-hybrid methods such as XYG3 or DSD-PBEhB95. Finally, we show that the SCS-dRPA75 method has reduced self-interaction and delocalization errors compared to the parent dRPA75 method and a slightly smaller static correlation error than the related PWRB95 method.
authors.affiliation: MTA-BME Lendület Quantum Chemistry Research Group, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics , H-1521 Budapest, Hungary.
authors.forename: Pál D
authors.identifier: http://orcid.org/0000-0002-7052-9677
authors.initials: PD
authors.lastname: Mezei
authors.affiliation: Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics , H-1521 Budapest, Hungary.
authors.forename: Gábor I
authors.initials: GI
authors.lastname: Csonka
authors.affiliation: Department of Physics, Temple University , Philadelphia, Pennsylvania 19122, United States.
authors.forename: Adrienn
authors.initials: A
authors.lastname: Ruzsinszky
authors.affiliation: MTA-BME Lendület Quantum Chemistry Research Group, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics , H-1521 Budapest, Hungary.
authors.forename: Mihály
authors.identifier: http://orcid.org/0000-0003-1080-6625
authors.initials: M
authors.lastname: Kállay