An Embedded Fragment Method for Molecules in Strong Magnetic Fields.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Molecular clusters are crucial in various chemical and physical processes.
• Accurate calculations for large molecular systems, especially under external fields, remain computationally challenging.
• Previous studies suggested magnetic fields strengthen hydrogen bonds in molecular clusters.

Purpose of the Study:

• To present an extended embedded fragment method for molecular cluster calculations incorporating strong external magnetic fields.
• To enable computationally tractable calculations for large systems using various quantum chemical methods with London atomic orbitals.
• To investigate the effect of strong magnetic fields on the binding properties of water clusters.

Main Methods:

• Extension of the embedded fragment method to include strong external magnetic fields.
• Implementation of calculations at Hartree-Fock, current-density-functional theory, Møller-Plesset perturbation theory, and coupled-cluster levels.
• Utilized London atomic orbitals for accurate magnetic field response calculations.

Main Results:

• Demonstrated computational tractability for large water clusters (up to 103 molecules) using triple-ζ basis sets.
• Observed enhanced binding within water clusters under strong magnetic fields.
• Found that enhanced binding is not due to strengthened hydrogen bonds but rather induced charge density build-up between monomer units at higher field strengths.

Conclusions:

• The developed method offers a computationally efficient way to study molecular clusters in strong magnetic fields.
• Strong magnetic fields enhance cluster binding through induced charge density, challenging previous assumptions about hydrogen bond strengthening.
• The approach is highly parallelizable and extends the reach of conventional computational chemistry methods.