Molecular Dynamics Driven by the Many-Body Expansion (MBE-MD)

• DOI: 10.1021/acs.jctc.1c00780
• Publication Date: 2021-11-01T18:43:47Z
• Authors: Joseph P. Heindel; Sotiris S. Xantheas
• Keywords: Energetics

We present a protocol for classical and nuclear quantum dynamics, in which the energies forces are generated by many-body expansion (MBE), apply it to water clusters using TTM2.1-F MB-Pol interaction potentials at various temperatures. carry out MBE-molecular dynamics (MD) dynamical simulations, of full system approximated two-, three-, four-body terms MBE, compare average potential vibrational density states with simulation, i.e., one no MBE is used. Our results indicate that thermally averaged energy from up term converges near-identical behavior simulation. The three-body makes substantial contribution (∼20%) energy, whereas necessary obtaining quantitatively accurate energetics forces, albeit making small each (∼2%). further show harmonic frequencies reproduced within few wavenumbers (cm-1) level slowest modes converge rank those involving strongest hydrogen bonds. Anharmonicity exacerbates this effect, so description needed achieve anharmonic hydrogen-bonded OH-stretching region. also discuss asymptotic scaling MBE-MD respect cost underlying evaluation, suggesting electronic structure methods scale least as N4, N being size system, result savings over traditional MD anticipate can evolve into powerful practical method, will allow highly ab initio simulations on much broader range molecular systems than be currently handled.