Tight-binding molecular dynamics systems

TIGHT-BINDING MOLECULAR DYNAMICS STUDIES OF COVALENT SYSTEMS... 

In the tight-binding molecular-dynamics scheme [13], the atomic motion in the system is governed by the following Hamiltonian ... 

The expression for the binding energy of a system with M atoms and N valence electrons in tight-binding molecular dynamics (TBMD) is given by... 

Recent advances in first-principles molecular dynamics (MD) calculations, which follow the Newtonian dynamics of classically treated nuclei, have made electronic-structure calculations applicable to the study of large systems where previously only classical simulations were possible. Examples of quantum-mechanical (QM) simulation methods are Born-Oppenheimer molecular dynamics (BOMD), Car-Parrinello molecular dynamics (CPMD), tight-binding molecular dynamics (TBMD), atom-centered density matrix propagation molecular dynamics (ADMPMD), and wavepacket ab idtb molecular dynamics (WPAIMD). 

Harvey SC, Tan RK-Z, Cheatham TE III (1998) The flying ice cube velocity rescaling in molecular dynamics leads to violation of energy equipartition. J Comput Chem 19 726-740 Lundberg M, Nishimoto Y, Irle S (2012) Delocalization errors in a Hubbard-like model consequences for density-functional tight-binding calculations of molecular systems. Int J Quant Chem 112 1701-1711... 

Beyond a certain system size, even DFT methods using conventional basis sets become computationally very intensive. In such situations, one has to take recourse to the use of solid-state physics methods like the pseudopotential plane wave or tight-binding methods [28,29]. As the systems become larger, Monte Carlo (MC) simulations and molecular dynamics simulations based on effective pair potentials (including two-body to multi-body interactions) are carried out. 

Although ab initio molecular orbital theory and density functional theory can be used to systematically improve the accuracy of X-Pol results for large systems, it is still impractical to use these methods to perform molecular dynamics simulations for an extended period of time. With increased computing power, this will become feasible in the future however, at present, it is desirable to use semiempirical molecular orbital models such as the popular approaches based on neglect of diatomic differential overlap (NDDO) or the more recent self-consistent-charge tight-binding density functional (SCC-method to model condensed-phase and biomacromolecules. 

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