The orbital-specific virtual local triples correction: OSV-L(T).

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Coupled cluster (CC) methods are accurate but computationally expensive for large systems.
• Local correlation methods approximate the CC ansatz to reduce computational cost.
• Previous local methods often relied on domain approximations for virtual spaces.

Purpose of the Study:

• To present a new local method for calculating perturbative triples corrections in coupled cluster.
• To develop a scheme based on orbital specific virtuals (OSVs) that avoids ad hoc truncations.
• To demonstrate linear scaling computational cost and high accuracy.

Main Methods:

• Development of a local coupled cluster method utilizing orbital specific virtuals (OSVs).
• A single threshold automatically defines pair and triple specific virtual spaces.
• Linear scaling computational cost is achieved through domain-specific virtual spaces.

Main Results:

• The OSV-based method recovers a similar fraction of correlation energy as previous methods at lower cost.
• Accuracy comparable to coupled cluster with singles and doubles and perturbative triples (CCSD(T)) is achieved for reaction energies.
• Application to guanine-cytosine dimers provides new complete-basis-set-limit estimates for interaction energies.

Conclusions:

• The OSV-local CC method offers an efficient and accurate approach for large-scale electronic structure calculations.
• The method achieves linear scaling computational cost, making it suitable for complex molecular systems.
• Accurate interaction energies for biologically relevant molecules like DNA base pairs can be obtained.