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Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Hydration free energies using semiempirical quantum mechanical Hamiltonians and a continuum solvent model with
Victor M Anisimov1, Claudio N Cavasotto
1School of Biomedical Informatics, University of Texas Health Science Center at Houston, 7000 Fannin Street, Houston, Texas 77030, United States.
The Journal of Physical Chemistry. B
|May 19, 2011
Summary
Optimized atomic parameters for the COnductor-like Screening MOdel (COSMO) improve quantum mechanical (QM) simulations of biomolecules in water. New parameters enhance accuracy for semiempirical QM calculations in condensed-phase chemical and biological systems.
Area of Science:
- Computational Chemistry
- Biomolecular Simulation
- Quantum Mechanics
Background:
- Accurate quantum mechanical (QM) simulations of biomacromolecules in aqueous environments are crucial for understanding biological processes.
- The COnductor-like Screening MOdel (COSMO) is a popular implicit solvent model for such simulations.
- Existing parameterizations may limit the accuracy of QM/COSMO for biomolecular systems.
Purpose of the Study:
- To optimize atomic radii and surface tension coefficients for the COSMO model.
- To enhance the accuracy of semiempirical QM calculations for biomacromolecules in aqueous solutions.
- To develop new parameter sets for various semiempirical Hamiltonians (AM1, PM3, PM5, RM1).
Main Methods:
- Optimization of COSMO atomic parameters (radii, surface tension coefficients).
- Reproduction of experimental hydration free energies for 507 neutral and 99 ionic molecules.
- Implementation of a multiple atomic-type scheme and scaled particle Claverie-Pierotti formalism for nonpolar contributions.
- Validation against AM1, PM3, PM5, and RM1 semiempirical Hamiltonians.
Main Results:
- Significant improvement in calculated hydration free energies.
- Average unsigned errors of 0.64, 0.66, 0.73, and 0.71 kcal/mol for neutral molecules with AM1, PM3, PM5, and RM1, respectively.
- Fast free energy calculations (0.5 s per molecule on a single processor).
Conclusions:
- The developed COSMO parameter sets enhance the quality of semiempirical QM calculations for biomolecular systems.
- These optimized parameters extend the applicability of QM methods to condensed-phase chemical and biological systems.
- The study provides a foundation for more accurate QM simulations of biomacromolecules in solution.
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