Prediction of 11B Quadrupole Coupling Constants in Molecules

Area of Science:

• Computational chemistry
• Quantum chemistry
• Spectroscopy

Background:

• Nuclear quadrupole coupling constants (NQCCs) are crucial for understanding molecular electronic structure.
• Accurate prediction of NQCCs often requires computationally intensive methods.
• The 11B nucleus is of interest in various chemical contexts.

Purpose of the Study:

• To evaluate the B3LYP/6-31G(df, p) model as a cost-effective alternative for calculating 11B NQCCs.
• To compare the accuracy of B3LYP with the established MP2/6-311G(3df, 3pd) method.
• To assess the performance across a range of molecules.

Main Methods:

• Density Functional Theory (DFT) using the B3LYP functional with the 6-31G(df, p) basis set.
• Second-order Møller–Plesset perturbation theory (MP2) with the 6-311G(3df, 3pd) basis set.
• Calculation of 11B nuclear quadrupole coupling constants for a set of molecules.

Main Results:

• The B3LYP model yielded a root mean square (rms) deviation of 0.059 MHz from experimental 11B NQCCs for 11 molecules.
• The MP2 model showed a slightly lower rms deviation of 0.049 MHz.
• The rms difference between the B3LYP and MP2 models was 0.036 MHz when tested on 25 molecules.

Conclusions:

• The B3LYP/6-31G(df, p) model is a viable and computationally efficient alternative for predicting 11B NQCCs.
• B3LYP offers a good balance between accuracy and computational cost compared to MP2.
• This finding facilitates broader computational studies involving 11B NQCCs.