R.E.D.

R.E.D. derives non-polarizable RESP (Restrained Electrostatic Potential) and ESP (Electrostatic Potential) atomic charges from quantum-mechanical electrostatic potentials to produce Tripos mol2 force-field libraries and topology data for molecular modeling and simulation.

Key Features:

• Charge Derivation: Computes non-polarizable RESP and ESP atomic charges from quantum-mechanical electrostatic potentials.
• Force Field Library Construction: Embeds derived charges into Tripos mol2 format and assembles force-field libraries for new molecules or molecular fragments.
• Integration with Quantum Mechanics Programs: Interfaces with quantum mechanics programs and the RESP program to obtain electrostatic potentials used for charge fitting.
• Two-Step Methodology: Prepares P2N files defining atom names, topology, and chemical equivalencing, then derives charges and builds force-field libraries with the option to generate comprehensive topology databases.

Scientific Applications:

• Force Field Development: Supports creation and refinement of molecular mechanics force fields by providing rigorously derived charges and library entries.
• Charge Validation: Enables validation of derived atomic charges against experimental data or other theoretical benchmarks.
• Molecular Dynamics Simulations: Supplies charge sets and Tripos mol2 force-field libraries to improve the accuracy and reliability of molecular dynamics simulations.

Methodology:

Preparation of P2N files (atom names, topology, chemical equivalencing); computation of quantum-mechanical electrostatic potentials via interfaced quantum mechanics programs and the RESP program; fitting of non-polarizable RESP or ESP charges; embedding charges in Tripos mol2 force-field libraries and optional generation of topology databases.