Molecular dynamics simulation of ion mobility in gases

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

A force field molecular dynamics method is developed to directly simulate ion drift in buffer gases driven by an electric field. The ion mobility and collision cross sections (CCSs) with relevance to ion mobility spectrometry can be obtained from the simulated drift velocity in high-density buffer gases (pressure ∼50 bars) and high electric fields (∼107 V/m). Compared to trajectory methods, the advantage of the molecular dynamics method is that it can simultaneously sample the internal dynamic motions of the ion and the ion-gas collisions. For ions with less than 100 atoms, the simulated collision cross section values can be converged to within ±1%-2% by running a 100 ns simulation for 5-19 h using one computer core. By using a set of element-based Lennard-Jones parameters that are not tuned for different atomic types in different molecules, the simulated collision cross sections for 15 small molecular ions (number of atoms ranging from 17 to 85, mass ranging from 74.1 to 609.4 g/mol) are consistent with experimental values: the mean unsigned error is 2.6 Å2 for He buffer gas and 4.4 Å2 for N2 buffer gas. The sensitivity of the simulated CCS values to random diffusion, drift velocity, electric field strength, temperature, and buffer gas density is examined.

Original languageEnglish (US)
Article number064109
JournalJournal of Chemical Physics
Volume148
Issue number6
DOIs
StatePublished - Feb 14 2018

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Molecular dynamics
Gases
Ions
molecular dynamics
buffers
Buffers
Computer simulation
collisions
gases
ions
simulation
cross sections
Electric fields
electric fields
Atoms
electric field strength
gas density
Density of gases
molecular ions
field theory (physics)

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Molecular dynamics simulation of ion mobility in gases. / Lai, Rui; Dodds, Eric D.; Li, Hui.

In: Journal of Chemical Physics, Vol. 148, No. 6, 064109, 14.02.2018.

Research output: Contribution to journalArticle

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