Density-functional tight-binding models
Work by Nir Goldman (LLNL) and collaborators using a modified version of the DFTB+ code, which can be hooked to LAMMPS through its library interface to perform quantum MD simulations. DFTB+ computes quantum density-functional forces via the semi-empirical tight-binding approximation; LAMMPS does the timestepping.
They have used this coupled framework to study a variety of interesting systems, as shown in these journal cover images. The first is synthesis of carbon fibers from graphite which has been liquified and evaporates due to a laser pulse. The second is a model of a laser pulse inducing a shock which triggers exothermic chemistry in hydrogen peroxide. The final example models the creation of prebiotic organic molecules via shock compression of icy materials, analogous to what may occur when a comet strikes the surface of the Earth.
Related publications
- Carbyne Fiber Synthesis within Evaporating Metallic Liquid Carbon, C. Cannella and N. Goldman, J. Phys. Chem. C 119, 21605 (2015). doi:10.1021/acs.jpcc.5b03781
- Ultrafast Shock Initiation of Exothermic Chemistry in Hydrogen Peroxide, M. R. Armstrong, J. M. Zaug, N. Goldman, I-F. W. Kuo, J. C. Crowhurst, W. M. Howard, J. A. Carter, M. Kashgarian, J. M. Chesser, T. W. Barbee, and S. Bastea, J. Phys. Chem. A 117, 13051 (2013). doi:10.1021/jp407595u
- Prebiotic Chemistry Within a Simple Impacting Icy Mixture, N. Goldman and I. Tamblyn, J. Phys. Chem. A 117, 5124 (2013). doi:10.1021/jp402976n