Performance of a nonempirical exchange functional from density matrix expansion: comparative study with different...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• The Tao-Mo (TM) meta-generalized gradient approximation offers high accuracy for exchange-correlation energy calculations.
• Understanding the performance of TM and its variants is crucial for accurate theoretical chemistry predictions.

Purpose of the Study:

• To comparatively evaluate the performance of the TM functional and a new variant, TMTPSS.
• To assess accuracy across various chemical systems including atoms, molecules, and hydrogen-bonded complexes.

Main Methods:

• Utilized eight well-established benchmark databases for calculations.
• Performed comparative studies on atomic, molecular, and hydrogen-bonded systems.
• Analyzed accuracy for properties like atomization energies, vibrational frequencies, and proton affinities.

Main Results:

• TMTPSS demonstrated superior accuracy for atomization energies, enthalpies of formation, harmonic vibrational frequencies, and atomic excitation energies compared to TM.
• TM functional showed better performance for proton affinities, molecular bond lengths, and hydrogen-bonded complexes.
• TMTPSS exhibited reduced accuracy for proton affinities, molecular bond lengths, and particularly for hydrogen-bonded complexes.

Conclusions:

• The TMTPSS functional offers improvements for certain properties but shows limitations in others.
• The choice between TM and TMTPSS depends on the specific chemical properties and systems being studied.
• Further development may be needed to enhance the accuracy of these functionals for all chemical applications.