Tailor-made force fields for crystal-structure prediction.

Area of Science:

• Computational chemistry
• Materials science
• Crystallography

Background:

• Accurate force fields are crucial for simulating molecular behavior in the crystalline state.
• Existing methods may lack precision for flexible molecules, necessitating improved parameterization strategies.

Purpose of the Study:

• To develop a general procedure for deriving comprehensive force-field parameters for flexible molecules in crystals.
• To validate the derived force fields by predicting crystal structures and comparing them with experimental data.

Main Methods:

• A hybrid quantum mechanics/empirical method combining solid-state density functional theory (DFT) with van der Waals corrections was employed.
• Force-field parameters were fitted to electrostatic potentials, energies, and forces derived from DFT calculations.
• The VASP program was utilized for all DFT computations.

Main Results:

• A tailor-made force field for cyclohexane-1,4-dione was successfully generated.
• Crystal structure prediction using the derived force field accurately identified the experimental crystal structure as the most stable.
• The methodology demonstrated success across five compounds, including those from a crystal structure prediction blind test, with low root-mean-square deviations in lattice energies.

Conclusions:

• The presented general procedure provides a robust method for creating accurate force fields for flexible crystalline materials.
• This approach enhances the reliability of crystal structure prediction and molecular modeling in the solid state.
• The validated methodology offers a powerful tool for materials design and discovery.