Relativistic Gaussian functions for atoms by fitting numerical results with adaptive nonlinear least-square...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Atomic physics

Background:

• Accurate atomic basis sets are crucial for computational chemistry.
• Relativistic effects become significant for heavy elements like mercury (Hg).

Purpose of the Study:

• To derive a relativistic Gaussian basis set for mercury (Hg).
• To evaluate the performance of the generated basis set for molecular and extended systems.

Main Methods:

• Fitting numerical relativistic atomic radial wave functions.
• Utilizing an adaptive nonlinear least-square algorithm with subset selection.
• Generating a new basis set through a multi-step procedure.

Main Results:

• A relativistic Gaussian basis set for Hg was successfully obtained through fitting.
• The derived basis set yielded reasonable results for Hg, HgO, and a Se atom chain.
• The initial fitted basis set failed due to a non-positive definite overlap matrix.

Conclusions:

• The developed fitting procedure provides a method for generating relativistic basis sets for heavy elements.
• Further refinement is needed to address issues like the positive definiteness of the overlap matrix for broader applicability.