Numerical examination of performance of some exchange-correlation functionals for molecules containing heavy elements

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Relativistic DFT

Background:

• Accurate prediction of molecular properties is crucial in chemistry.
• Heavy elements present unique challenges due to relativistic effects.
• Density Functional Theory (DFT) is a widely used computational method.

Purpose of the Study:

• To numerically examine the performance of 17 exchange-correlation functionals.
• To assess their accuracy for molecules containing heavy elements.
• To compare their performance against molecules with only light elements.

Main Methods:

• Four-component relativistic Density DFT calculations were employed.
• 17 different exchange-correlation functionals were tested.
• Performance was evaluated based on bond lengths, frequencies, and bond energies.

Main Results:

• Functionals generally showed similar accuracy for heavy element molecules as for light element molecules, except for bond lengths.
• Local Density Approximation (LDA) and OP86 performed well for bond lengths and frequencies but poorly for bond energies.
• BP86 and GP86 offered average accuracy, while LYP performed poorly. B97GGA-1 showed promise, but other complex functionals did not impress.

Conclusions:

• The choice of exchange-correlation functional significantly impacts the accuracy of relativistic DFT calculations for heavy element molecules.
• LDA and OP86 are recommended for accurate bond lengths and frequencies.
• Further development of functionals is needed for reliable prediction of bond energies involving heavy elements.