Assessment of Density Functional Approaches for Carbon Dioxide Dimerization and Solid-State Properties

Area of Science:

• Computational chemistry
• Materials science
• Quantum mechanics

Background:

• Accurate description of intermolecular forces is crucial for understanding molecular interactions.
• Density Functional Theory (DFT) is a powerful tool for electronic structure calculations.
• Van der Waals (vdW) dispersion corrections are essential for describing weak interactions.

Purpose of the Study:

• To assess the performance of various exchange-correlation functionals with vdW dispersion corrections in SIESTA for CO2 homodimer interactions.
• To identify the most stable configurations of CO2 homodimers.
• To provide a benchmark for CO2-CO2 interactions and force field development.

Main Methods:

• Density Functional Theory (DFT) calculations using SIESTA.
• Implementation and testing of multiple vdW functionals (BH, C09, KBM, LMKLL, VV) and GGA.
• Calculation of interaction energies, vibrational modes, and solid-phase properties.
• Comparison with high-level CCSD-(T)/SAPT calculations and experimental data.

Main Results:

• T-shaped (TS) and parallel-displaced (PD) geometries were found to be the most stable CO2 homodimer configurations.
• The vdW-DF-C09 functional demonstrated excellent agreement with high-level calculations for the PD configuration.
• vdW-DF-C09 accurately reproduced experimental vibrational modes for solid CO2.
• Comparative analysis provided insights for force field parametrization.

Conclusions:

• The vdW-DF-C09 functional is highly suitable for describing CO2-CO2 interactions.
• This study establishes a reliable benchmark for CO2 interactions.
• Findings support future force field development and multiscale modeling of CO2 systems.