Computational (bio)chemistry research has yielded this first-of-its-kind, high-level theoretical study for reference that compares hydrogen bonds between natural DNA nucleobase pairs and synthetic Hachimoji DNA base pairs.

J. Chem. Inf. Model. 2023, 63, 10, 3150–3157

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Study Focus: Evaluated the accuracy of dimer geometries (not just interaction energies) obtained using various electronic structure methods for 21 van der Waals dimers.

Reference Standard: High-level CCSD(T)/CBS calculations were used as the benchmark for geometry optimization.

Methods Assessed: Included MP2, MP2D, MP2.5, CCSD, and CCSD(T) with basis sets ranging from double- to quadruple-zeta.

Metrics for Comparison: Deviations in atomic coordinates (LRMSD), center-of-mass distances (∆dCOM), interaction energies, and rotational constants.

Key Findings: Larger basis sets (beyond double-zeta) significantly improve geometry accuracy. Frozen core approximation has a negligible impact on geometries. Counterpoise correction can worsen geometry quality with double-zeta basis sets. Several methods achieve <0.1 Å LRMSD and ∆dCOM across all dimers.

Best Trade-Off: MP2D with aug-cc-pVTZ basis set provided the best balance of accuracy and computational cost, with average LRMSD and ∆dCOM of 0.02 Å. 

J. Chem. Phys. 2025 , 162, 174106.

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