Domain-Based Local Pair Natural Orbital Version of Mukherjee’s State-Specific Coupled Cluster Method

Abstract

This article reports development of a local variant of Mukherjee's state-specific multireference coupled cluster method based on the domain-based pair natural orbital approach (DLPNO-MkCC). The current implementation is restricted to connected single and double excitations and model space with up to biexcited references. The performance of the DLPNO-MkCCSD was tested on calculations of tetramethyleneethane. The results show that above 99.9% of the correlation energy was recovered, with respect to the conventional MkCC method. To demonstrate the applicability of the method to large systems, singlet-triplet gaps of triangulene and bis(1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidine-2-ylidene)beryllium complex were studied. For the last system (105 atoms), we were able to perform a calculation in cc-pVTZ with 2158 basis functions on a single CPU in less than 9 days.

Interactions of Solvated Electrons with Nucleobases: The Effect of Base Pairing

“…However, wave‐function based methods converge very slowly with respect to the basis set size and are impractical to be used for large anions. The newly developed domain‐based local pair natural orbital (DLPNO) implementation of the equation of motion coupled cluster (EA‐EOM‐DLPNO‐CCSD) method can be applied to electron attached states of large molecules with systematic controllable accuracy. We have recently developed a QM/MM protocol based on EA‐EOM‐DLPNO‐CCSD method, which can treat the ground and excited states of the solvated anion on an equal footing and can reproduce the experimentally reported rate of reduction of solvated nucleobases .…”

The Adsorption of Small Molecules on the Copper Paddle-Wheel: Influence of the Multi-Reference Ground State

“…The latter can be accounted as an “accessible version” of the “golden standard”. Finally, we performed a few benchmark calculations with a computationally expensive DLPNO–MR–CCSD approach (DLPNO–MkCCSD in the notation of developers [ 78 , 79 , 80 , 81 ]). All these calculations were performed as single-points on PBE-optimized molecular geometries ( Figure 2 ).…”

An efficient Fock space multi-reference coupled cluster method based on natural orbitals: Theory, implementation, and benchmark

“…The use of MP2 natural orbitals has emerged as an effective way of reducing the computational cost of the ground state coupled cluster calculations. Among the various flavors of natural orbital available, we have used the domain-based local pair natural orbital (DLPNO) framework of Neese and co-workers [90][91][92][93][94][95][96][97][98] . In this framework, the occupied space is expanded in terms of localized occupied orbitals, and the virtual space is expanded in terms of correlation domain using projected atomic orbitals (PAOs) 99 .…”