Efficient molecular density functional theory using generalized spherical harmonics expansions

Area of Science:

• Computational chemistry
• Statistical mechanics
• Physical chemistry

Background:

• Molecular density functional theory (DFT) is crucial for understanding solvation.
• Representing molecular solvent density (ρ(r,Ω)) involves complex spatial (r) and orientational (Ω) components.
• Previous methods for angular convolution products were computationally expensive.

Purpose of the Study:

• To introduce generalized spherical harmonics for efficient molecular density representation in DFT.
• To accelerate the calculation of solvation free energy and solvent structure.
• To enable systematic studies of complex solutes in various solvents.

Main Methods:

• Utilizing generalized spherical harmonics to represent molecular solvent density.
• Minimizing the density functional with respect to ρ(r,Ω).
• Replacing computationally intensive angular convolutions with simple products of harmonic projections.

Main Results:

• Demonstrated the suitability of generalized spherical harmonics for space and orientation density representation.
• Achieved a dramatic speedup in calculation time for molecular DFT.
• Enabled exploration of nanometric solutes in arbitrary solvents within minutes.

Conclusions:

• Generalized spherical harmonics offer a significant computational advantage for molecular DFT.
• The method facilitates efficient calculation of solvation free energy and microscopic solvent structure.
• The formalism is applicable to diverse molecules and solvent systems, including water.