An efficient implementation of two-component relativistic exact-decoupling methods for large molecules.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Relativistic quantum mechanics

Background:

• Relativistic effects are crucial for accurate calculations of heavy elements.
• The exact-decoupling method accounts for spin-orbit coupling.
• Evaluating the relativistic Hamiltonian is computationally intensive for large systems.

Purpose of the Study:

• To present an efficient algorithm for one- and two-component relativistic exact-decoupling calculations.
• To accelerate the bottleneck step in relativistic calculations: the construction of the relativistic one-electron Hamiltonian.
• To enable efficient relativistic density functional calculations for large molecular systems.

Main Methods:

• Implementation of an efficient algorithm for relativistic exact-decoupling.
• Application of the local DLU scheme to accelerate Hamiltonian construction.
• Utilizing resolution-of-identity density-fitting and point group symmetry for acceleration.
• Calculation of cohesive energies for silver clusters.

Main Results:

• A minimal matrix operation count for exact-decoupling protocols is established.
• The developed algorithm significantly accelerates relativistic calculations.
• Successful application to large silver clusters (up to 309 atoms).

Conclusions:

• The new implementation enables efficient two-component relativistic density functional calculations.
• The method is capable of handling large molecular systems, as demonstrated with silver clusters.
• Accurate calculation of cohesive energies and extrapolation to bulk properties is feasible.