LAMMPS and the LATTE density functional tight-binding code

C. F. A. Negre (1), R. T. Perriot (1), M. J. Cawkwell (1), A. M. N. Niklasson (1) and S. J. Plimpton (2)

(1) Los Alamos National Laboratory(2) Sandia National Laboratories

LATTE is a molecular dynamics package based around
self-consistent-charge density functional tight binding theory (DFTB)
**1, 3, 2**. It enables the linear scaling construction of the density
matrix by applying a recursive Fermi operator expansion in sparse
matrix algebra **4**. It also provides an implementation of the extended
Lagrangian Born-Oppenheimer molecular dynamics formalism (XL-BOMD)
which provides long-term energy conservation in microcanonical
trajectories while removing the expensive, iterative
self-consistent eld procedure at each time step. **5**. As part of an
exascale computing project **6**, the LATTE code now can be compiled as
a library and bindings for integration with the LAMMPS molecular
dynamics code **7** have been developed. With this implementation it is
possible to most of the LAMMPS functionalities with forces calculated
at the DFTB level of theory. Results that highlight the power of the
combined codebases will be presented. These include geometry
optimizations, linear scaling molecular dynamics simulation of several
thousand atoms, and the determination of transition barriers for bond
breaking using the nudged elastic band method.

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**5** A. M. N. Niklasson, \Extended born-oppenheimer molecular
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**6** \The exascale computing project,"
2017. https://exascaleproject.org/exascale-computing-project/.

**7** S. Plimpton, \Fast parallel algorithms for short-range molecular
dynamics," J. Comp. Phys., vol. 117, p. 1, 1995.