Smooth potential-energy surfaces in fragmentation-based local correlation methods for periodic systems

Hansen, Audun Skau; Aurbakken, Einar; Pedersen, Thomas Bondo

doi:10.1080/00268976.2021.1896046

Cited by 1 publication

(1 citation statement)

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“…These methods can be classified into two categories. The first, often referred to as direct local correlation methods, treats the entire molecule at once by omitting insignificant contributions. − The second category is the cluster-based methods, obtaining the total correlation energy as the sum of contributions from smaller clusters containing a subset of occupied LMOs and their virtual orbitals. − Although both direct and cluster-based methods can achieve a linear scaling computational cost with the system size, the cluster-based methods require much less storage and thus are applicable to much larger systems. Resolution-of-the-identity (RI) − approximation, a technique employed to accelerate electronic structure calculations by approximating the four-index two-electron integrals with two- and three-index integrals, can be combined with local correlation methods to further reduce the computational costs.…”

Section: Introductionmentioning

confidence: 99%

Analytical Gradient Using Cluster-in-Molecule RI-MP2 Method for the Geometry Optimizations of Large Systems

Zheng,

Ni,

Wang

et al. 2024

J. Chem. Theory Comput.

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We present an efficient analytical energy gradient algorithm for the cluster-in-molecule resolution-of-identity second-order Møller–Plesset perturbation (CIM-RI-MP2) method based on the Lagrange multiplier method. Our algorithm independently constructs the Lagrangian formalism within each cluster, avoiding the solution of the coupled-perturbed Hartree–Fock (CPHF) equation for the whole system. Due to this feature, the computational cost of the CIM-RI-MP2 gradients is much lower than that of other local MP2 algorithms. Benchmark calculations of several molecules containing up to 312 atoms demonstrate the general applicability of our CIM-RI-MP2 gradient algorithm. The optimized structure of a 244-atom molecule using the CIM-RI-MP2 method with the cc-pVDZ basis set is in good agreement with the corresponding crystal structure. A single-point gradient calculation conducted for a molecular cage containing 972 atoms and 9612 basis functions takes 48 h on 25 nodes, utilizing a total of 600 CPU cores. The present CIM-RI-MP2 gradient program is applicable for obtaining the optimized geometries of large systems with hundreds of atoms.

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