Performance of Relativistic Effective Core Potentials for Closed-Shell Superheavy Element Halides in DFT and TDDFT...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Relativistic Effects

Background:

• Pseudopotentials (PPs) are crucial for density functional theory (DFT) and time-dependent DFT (TDDFT) calculations.
• The accuracy of PPs, especially with spin-orbit coupling (SOC) for superheavy elements, remains under-investigated.
• Superheavy elements exhibit strong SOC effects, necessitating accurate theoretical treatments.

Purpose of the Study:

• To evaluate the performance of small-core energy-consistent PPs for superheavy element halides.
• To compare PP-based DFT and TDDFT results with all-electron calculations, including SOC.
• To assess the impact of exchange-correlation functionals and basis sets on PP accuracy.

Main Methods:

• Utilized small-core energy-consistent PPs developed by Stuttgart groups.
• Performed DFT calculations for ground-state properties (bond lengths, force constants, dissociation energies).
• Conducted TDDFT calculations for vertical excitation energies.
• Compared results with all-electron Dirac-Coulomb(-Gaunt) Hamiltonian calculations.

Main Results:

• PPs demonstrated good agreement with all-electron results for both scalar relativistic and SOC calculations.
• Deviations from all-electron results were largely insensitive to the choice of exchange-correlation functionals.
• Basis set effects on calculated properties were minimal in PP calculations.
• The PPs provided reasonable accuracy for superheavy element halides.

Conclusions:

• Small-core energy-consistent PPs are reliable for DFT and TDDFT studies of superheavy element halides.
• These PPs effectively capture strong SOC effects in superheavy elements.
• The findings support the use of these PPs for future research on superheavy element compounds.