Analytic atomic gradients in the fermi-löwdin orbital self-interaction correction

Area of Science:

• Computational chemistry
• Quantum chemistry
• Materials science

Background:

• Self-interaction error is a significant issue in electronic structure calculations.
• The Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method aims to mitigate this error.
• Accurate atomic forces are crucial for geometry optimization and molecular dynamics.

Purpose of the Study:

• To derive and implement the analytic expression for atomic forces within the FLO-SIC method.
• To validate the accuracy of these analytic forces through numerical comparisons.
• To enable routine self-interaction-free geometrical relaxations of molecules.

Main Methods:

• Derivation of the complete analytic expression for atomic forces, including Hellmann-Feynman and Pulay terms.
• Implementation of the analytic force expression within the FLO-SIC framework.
• Extensive numerical testing and comparison against finite difference methods.

Main Results:

• The complete analytic expression for FLO-SIC atomic forces was successfully derived and implemented.
• Analytic forces demonstrate high numerical accuracy when compared to finite difference calculations.
• Equilibrium molecular structures were obtained using the newly developed analytic forces.

Conclusions:

• The developed analytic forces for FLO-SIC are numerically accurate and reliable.
• This work facilitates self-interaction-free geometrical optimizations for molecules.
• Routine application of FLO-SIC for accurate molecular structure determination is now feasible.