Variational and diffusion Monte Carlo study of post-d group 13-17 elements.

Area of Science:

• Computational chemistry
• Quantum mechanics
• Atomic and molecular physics

Background:

• Accurate theoretical predictions are crucial for understanding the chemistry of heavier elements.
• Post-d elements present unique challenges due to relativistic effects.

Purpose of the Study:

• To perform ab initio calculations on first-, second-, and third-row post-d elements.
• To assess the accuracy of quantum Monte Carlo methods for these systems.
• To benchmark molecular properties like dissociation energies and vibrational frequencies.

Main Methods:

• Variational and diffusion Monte Carlo calculations.
• Utilized scalar-relativistic energy-consistent Hartree-Fock pseudopotentials.
• Employed large basis sets for comparison.

Main Results:

• Calculated ionization energies and electron affinities for first- and second-row elements agree well with experiment and CCSD(T) results.
• Third-row element calculations show excellent agreement with CCSD(T) energies.
• Benchmark calculations for diatomic molecules and hydrides are presented.

Conclusions:

• Quantum Monte Carlo methods, with appropriate pseudopotentials, provide accurate results for post-d elements.
• The study validates the use of these methods for heavier elements where relativistic effects are significant.
• Reliable data for molecular properties of these systems have been generated.