Benchmark interaction energies for biologically relevant noncovalent complexes containing divalent sulfur

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Molecular Interactions

Background:

• Molecules with divalent sulfur atoms engage in significant noncovalent interactions.
• Accurate computation of these interaction energies necessitates a precise description of electron correlation effects.
• High-accuracy ab initio quantum chemical methods are essential for reliable energy calculations.

Purpose of the Study:

• To compute accurate noncovalent interaction energies for biologically relevant complexes containing divalent sulfur.
• To compare the performance of coupled-cluster theory with single and double substitutions and perturbative triple substitutions extrapolated to the complete basis set (CCSD(T))/CBS limit and the correlation-consistent Composite Approach (ccCA).

Main Methods:

• Utilized eight-point estimated CCSD(T)/CBS dissociation curves along the noncovalent interaction vector for each complex.
• Calculated interaction energies using the correlation-consistent Composite Approach (ccCA) for comparative analysis.

Main Results:

• On average, CCSD(T)/CBS and ccCA methods yielded interaction energies within 0.1 kcal mol(-1) of each other.
• Demonstrated high accuracy and agreement between the two sophisticated ab initio methods for sulfur-containing complexes.

Conclusions:

• The computed interaction energies provide a reliable benchmark for developing and validating less computationally intensive methods.
• Findings support the use of CCSD(T)/CBS and ccCA for accurate noncovalent interaction energy calculations in sulfur-containing systems.