Insight on Gaussian Basis Set Truncation Errors in Weak to Intermediate Magnetic Fields with an Approximate...

Area of Science:

• Quantum Chemistry
• Atomic Physics
• Computational Chemistry

Background:

• Strong magnetic fields, like those on white dwarfs, significantly alter atomic and molecular electronic structures.
• Existing Gaussian basis sets, optimized for zero field, introduce substantial truncation errors in high magnetic field calculations.

Purpose of the Study:

• To identify the limitations of Gaussian basis sets in atomic calculations under strong magnetic fields.
• To guide the development of improved basis sets for accurate quantum chemical computations in magnetic fields.

Main Methods:

• Performed fully numerical electronic structure calculations at the complete basis set (CBS) limit for light atoms (Z=1-18).
• Conducted finite-field calculations using various Gaussian basis sets, including the commonly used aug-cc-pVTZ.
• Introduced a real-orbital approximation for the magnetic-field Hamiltonian.

Main Results:

• Significant discrepancies were observed between fully numerical CBS limit calculations and approximate Gaussian basis set results (e.g., aug-cc-pVTZ).
• The aug-cc-pVTZ basis set showed considerable errors in calculations of atomic states across a range of magnetic field strengths (0 to 0.6 B0).
• A specialized AHGBSP3-9 basis set demonstrated much smaller errors, highlighting potential for improvement.

Conclusions:

• Standard Gaussian basis sets are inadequate for accurate atomic electronic structure calculations in strong magnetic fields.
• There is a clear need for developing and refining Gaussian basis sets specifically designed for finite magnetic field conditions.
• The findings provide a roadmap for creating more reliable computational tools for studying matter in extreme magnetic environments.