Coupled Cluster Valence Bond Method: Efficient Computer Implementation and Application to Multiple Bond Dissociations...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Strong correlation physics

Background:

• Strong correlation (SC) poses challenges for standard quantum chemical methods.
• Accurate modeling of bond breaking and delocalized systems is crucial in chemistry.

Purpose of the Study:

• To introduce an efficient implementation of the coupled cluster valence bond (CCVB) model.
• To demonstrate CCVB's capability in describing strong correlation effects during bond dissociation.
• To assess CCVB's performance on extended π-systems and large molecules.

Main Methods:

• Efficient implementation of the coupled cluster valence bond (CCVB) model.
• Application to symmetric dissociation of sulfur allotropes (S6, S8).
• Calculations on a series of acenes with up to 228 correlated electrons.

Main Results:

• CCVB accurately captures essential strong correlation effects, ensuring correct energy profiles during bond breaking.
• The model maintains spin symmetry and size extensivity.
• CCVB successfully treated dissociation of S6 and S8 into triplet S atoms.
• Analysis of large acenes revealed signatures of multi-electron strong correlation and partial delocalization.

Conclusions:

• The efficient CCVB implementation is suitable for studying strong correlation in various chemical systems.
• CCVB provides a robust framework for investigating bond breaking and delocalized electronic structures.
• The method shows promise for exploring complex phenomena in extended π-systems.