Header

UZH-Logo

Maintenance Infos

Large scale MD simulations of nucleation


Diemand, Jürg; Angélil, Raymond; Tanaka, Kyoko K; Tanaka, Hidekazu (2013). Large scale MD simulations of nucleation. In: Nucleation and Atmospheric Aerosols, Fort Collins, Colorado, USA, 23 June 2013 - 28 June 2013, 19-22.

Abstract

We present preliminary results from large scale molecular dynamics (MD) simulations of homogenous vapor to liquid nucleation. The simulations contain between one and eight billion Lennard-Jones atoms and were run for up to 56 million time-steps. The large particle numbers (over 104 times larger than previous simulations, see e.g. [2]) have several advantages: i) Resolving and quantifying nucleation at low supersaturations becomes possible within an accessible number of simulation time-steps, in spite of the very slow nucleation. ii) Even after forming many stable droplets the depletion of the vapor phase is negligible, i.e. the supersaturation remains constant during the simulations. iii) Excellent statistics on liquid droplet abundances and microscopic properties over a wide range in droplet sizes. iv) Simulations can be run efficiently on a large number of cpus. First, direct comparisons to laboratory experiments[6] are now possible: we find excellent agreement in the nucleation rates at kT = 0.3ɛ and somewhat lower rates in the simulations at kT = 0.4ɛ. At low temperatures, modified classical nucleation theory significantly underestimates the nucleation rates (by up to 109) and at kT = 1.0ɛ it overestimates the nucleation rates by up to 105. The semi-phenomenological model[3] matches the nucleation rates and the cluster size distributions found in previous MD simulations at higher supersaturations quite well[2]. But at the lower supersaturations probed here, its predictions differ from the MD results by large factors (up to 103.5). We will also present MD results on cluster size distributions, free energy functions, sticking probabilities and condensation and evaporation rates. The microscopic properties (shapes, density profiles, binding energies, etc.) of the large numbers of droplets formed are presented in a separate contribution to this conference (Angélil et. al).

Abstract

We present preliminary results from large scale molecular dynamics (MD) simulations of homogenous vapor to liquid nucleation. The simulations contain between one and eight billion Lennard-Jones atoms and were run for up to 56 million time-steps. The large particle numbers (over 104 times larger than previous simulations, see e.g. [2]) have several advantages: i) Resolving and quantifying nucleation at low supersaturations becomes possible within an accessible number of simulation time-steps, in spite of the very slow nucleation. ii) Even after forming many stable droplets the depletion of the vapor phase is negligible, i.e. the supersaturation remains constant during the simulations. iii) Excellent statistics on liquid droplet abundances and microscopic properties over a wide range in droplet sizes. iv) Simulations can be run efficiently on a large number of cpus. First, direct comparisons to laboratory experiments[6] are now possible: we find excellent agreement in the nucleation rates at kT = 0.3ɛ and somewhat lower rates in the simulations at kT = 0.4ɛ. At low temperatures, modified classical nucleation theory significantly underestimates the nucleation rates (by up to 109) and at kT = 1.0ɛ it overestimates the nucleation rates by up to 105. The semi-phenomenological model[3] matches the nucleation rates and the cluster size distributions found in previous MD simulations at higher supersaturations quite well[2]. But at the lower supersaturations probed here, its predictions differ from the MD results by large factors (up to 103.5). We will also present MD results on cluster size distributions, free energy functions, sticking probabilities and condensation and evaporation rates. The microscopic properties (shapes, density profiles, binding energies, etc.) of the large numbers of droplets formed are presented in a separate contribution to this conference (Angélil et. al).

Statistics

Altmetrics

Downloads

30 downloads since deposited on 11 Feb 2014
9 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Conference or Workshop Item (Paper), not refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Event End Date:28 June 2013
Deposited On:11 Feb 2014 08:19
Last Modified:08 Aug 2017 12:01
Publisher:American Institute of Physics
Series Name:AIP Conference Proceedings
ISSN:0094-243X
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1063/1.4803194

Download

Preview Icon on Download
Preview
Content: Published Version
Filetype: PDF
Size: 442kB
View at publisher

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations