Transferable density functional tight binding for carbon, hydrogen, nitrogen, and oxygen: Application to shock compression

Journal Article · Thu Jan 10 00:00:00 EST 2019 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.5063385· OSTI ID:1492539

Cawkwell, M. J.  ^[1]; Perriot, R. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

A new parameterization for density functional tight binding (DFTB) theory, lanl31, has been developed for molecules containing carbon, hydrogen, nitrogen, and oxygen. Optimal values for the Hubbard Us, on-site energies, and the radial dependences of the bond integrals and repulsive potentials were determined by numerical optimization using simulated annealing to a modest database of ab initio-calculated atomization energies and interatomic forces. The transferability of the optimized DFTB parameterization has been assessed using the CHNO subset of the QM-9 database [R. Ramakrishnan et al., Sci. Data, 1, 140022 (2014)]. These analyses showed that the errors in the atomization energies and interatomic forces predicted by our model are small and in the vicinity of the di erences between density functional theory calculations with di erent basis sets and exchange-correlation functionals. Good correlations between the molecular dipole moments and HOMO-LUMO gaps predicted by lanl31 and the QM-9 data set are also found. Furthermore, the errors in the atomization energies and forces derived from lanl31 are signi cantly smaller than those obtained from the ReaxFF-lg reactive force eld for organic materials [L. Liu et al., J. Phys. Chem. A, 115, 11016 (2011)]. The lanl31 DFTB parameterization for C, H, N, and O has been applied the to the molecular dynamics simulation of the principal Hugoniot of liquid nitromethane, liquid benzene, liquid nitrogen, pentaerythritol tetranitrate, trinitrotoluene, and cyclotetramethylene tetranitramine. The computed and measured Hugoniot loci are in excellent agreement with experiment and we discuss the sensitivity of the loci to the underestimated shock heating that is a characteristic of classical molecular dynamics simulations.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1492539
• Report Number(s): LA-UR-18-29043
• Journal Information: Journal of Chemical Physics, Vol. 150, Issue 2; ISSN 0021-9606
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY