Development of Divide‐and‐Conquer Density‐Functional Tight‐Binding Method for Theoretical Research on Li‐Ion Battery

Abstract

The density‐functional tight‐binding (DFTB) method is one of the useful quantum chemical methods, which provides a good balance between accuracy and computational efficiency. In this account, we reviewed the basis of the DFTB method, the linear‐scaling divide‐and‐conquer (DC) technique, as well as the parameterization process. We also provide some refinement, modifications, and extension of the existing parameters that can be applicable for lithium‐ion battery systems. The diffusion constants of common electrolyte molecules and LiTFSA salt in solution have been estimated using DC‐DFTB molecular dynamics simulation with our new parameters. The resulting diffusion constants have good agreement to the experimental diffusion constants.

Featured properties of Li+-based battery anode: Li4Ti5O12

“…That is to say that the extremely non-uniform hopping integrals that are associated with various orbital hybridizations are rather difficult to achieve in order to t the main features of the rst-principles band structure. It seems that obtaining a reliable tight-binding model in Li + -based anode, 73 cathode 73 and electrolyte materials 73 will become an open issue, since it is relatively easy to understand the essential physical/material/chemical properties 74 from the concise pictures.…”

Dcdftbmd: Divide‐and‐Conquer Density Functional Tight‐Binding Program for Huge‐System Quantum Mechanical Molecular Dynamics Simulations

“…The benchmark calculations showed that simulation of one MD step for water system consisting of a few millions of atoms is completed within minutes using more than one hundred thousands of cores . The developed program has acquired robustness to the reactive system by means of grid box type fragments and enabled QM‐based MD simulations for systems consisting of from hundreds to thousands of atoms routinely when using laboratory workstation and/or moderate computer resources …”

“…[52] The developed program has acquired robustness to the reactive system by means of grid box type fragments and enabled QM-based MD simulations for systems consisting of from hundreds to thousands of atoms routinely when using laboratory workstation and/or moderate computer resources. [53][54][55][56][57][58][59][60][61] Although the parallelized DC-DFTB calculation has bridged the gap of system size existing between QM-based and classical MD simulations, further integrating advanced extensions into the program is necessary to allow the user to facilitate his or her theoretical analysis beyond the straightforward MD simulation under the plain DC-DFTB potential energy surfaces (PES). For example, timescale of DC-DFTB-based MD simulation is typically limited within nanoseconds, which makes it difficult to study chemical reactions with high energy barrier and to sample slow motion events including protein folding and arrangement of molecular aggregates.…”

Hierarchical parallelization of divide‐and‐conquer density functional tight‐binding molecular dynamics and metadynamics simulations

“…To date, fast large‐scale chemical reaction simulations combining DFTB with DC have been demonstrated for MD [ 57–64 ] and MetaD [ 65,66 ] (DC‐DFTB‐MD/MetaD). Herein, the extension of DC‐DFTB‐MD/MetaD for running simulations simultaneously for a set of geometries in the same system called walkers or replicas is reported to improve sampling and free energy evaluation efficiency.…”

“…[50,51] Enhanced sampling methods have been recently applied to DFTB-MD, resulting in novel DFTB-REMD, [52] DFTB-REUS, [53,54] and DFTB-MetaD methods. [55,56] To date, fast large-scale chemical reaction simulations combining DFTB with DC have been demonstrated for MD [57][58][59][60][61][62][63][64] and MetaD [65,66] (DC-DFTB-MD/MetaD). Herein, the extension of DC-DFTB-MD/MetaD for running simulations simultaneously for a set of geometries in the same system called walkers or replicas is reported to improve sampling and free energy evaluation efficiency.…”