The density functional-based tight binding (DFTB) method
has seen
a rise in adoption for materials modeling, as it offers significant
improvement in scalability with accuracy comparable to the density
functional theory (DFT) when good parameterizations exist. The cost
reduction in DFTB compared to DFT is achieved by the pre-parameterization
of the elements of the Hamiltonian matrix as well as the repulsion
potential between all pairs of atoms. Parameterization for new systems
with accuracies competitive with DFT in specific applications requires
specialized manpower and computational resources. This prevents the
application of the DFTB method to systems for which it was not parameterized.
In this work, we explore an approach to address the problem of missing
parameters of DFTB by modeling the interactions with missing Slater–Koster
parameters with an interatomic interaction potential. When the distance
between two atoms modeled at the force-field level is sufficiently
large, the approach results in accurate structural and electronic
properties. The resulting calculation is therefore a hybrid between
DFTB and molecular mechanics, a pure DFTB for atoms with a complete
set of interatomic parameterizations, and a mix between DFTB and molecular
mechanics for atoms with a missing interatomic parameterization. The
approach is expected to be particularly useful for hybrid materials
and interfaces. The method is tested on the examples of 2D materials,
mixed oxides, and a large-scale calculation of an oxide–oxide
interface.
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