Achievement
A scalable extension of fragment molecular orbital density-functional tight-binding (FMO-DFTB) to include a long-range corrected (LC) functional specifically designed to mitigate self-interaction error, called the FMO-LC-DFTB method, that provides a robust method capable of simulating zwitterionic systems.
Significance and Impact
The computational scaling of the new FMO-LC-DFTB method with system size N is shown to be almost linear, O(N1.13−1.28), and its numerical accuracy is established for a variety of representative systems including neutral and charged polypeptides. This means that for the first time, DFTB-based approaches can be used for the large-scale simulation (both structural optimization and dynamics) of zwitterionic species in the gas phase or in solutions with weakly polar solvents, or in systems where charges are buried deep inside their center, away from surfaces accessible to the solvent.
Research Details
- Fragment molecular orbital density-functional tight-binding (FMO-DFTB) is combined with a long-range corrected (LC) functionalè FMO-LC-DFTB.
- Validation of key energetic pair interaction energies between fragments for two mini-proteins
- FMO-LC-DFTB molecular dynamics of four charge states of the Trp-cage protein in the gas phase for 1 nanosecond.
- Stochastic searches for the global minimum structure of an EMIM nitrate ionic liquid cluster containing up to 2300 atoms.
Overview
Dynamic chemical processes in zwitterionic systems, such as biopolymers, ionic liquids, salt solutions, or metal−organic frameworks, have received considerable attention because of their fundamental importance in diverse fields such as energy conversion, medical applications, and catalysis. Detailed atomic-level understanding of ion transport reactive dynamics is needed to allow the rational design of a material to enhance its ionic conductivity. However, a fully quantum chemical study of these reactive processes is difficult because of the required long simulation time scale and large system size, often ranging in the tens of thousands of atoms. Here we have been able to bridge these gaps by developing a scalable extension of the fragment molecular orbital density-functional tight-binding (FMO-DFTB) that includes a long-range corrected (LC) functional specifically designed to mitigate self-interaction error, thus providing a robust method capable of simulating zwitterionic systems.
Citation and DOI:
“The Fragment Molecular Orbital Method Based on Long-Range Corrected Density-Functional Tight-Binding”, Van Quan Vuong,† Yoshio Nishimoto,‡ Dmitri G. Fedorov,¶ Bobby G. Sumpter,§ Thomas A. Niehaus,∥ Stephan Irle,§,⊥ J. Chem. Theory Comp. DOI: 10.1021/acs.jctc.9b00108 (2019).
Last Updated: May 28, 2020 - 4:06 pm