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ReaxFF-lg: Correction of the ReaxFF Reactive Force Field for London Dispersion, with Applications to the Equations of State for Energetic Materials

Liu, Lianchi and Liu, Yi and Zybin, Sergey V. and Sun, Huai and Goddard, William A., III (2011) ReaxFF-lg: Correction of the ReaxFF Reactive Force Field for London Dispersion, with Applications to the Equations of State for Energetic Materials. Journal of Physical Chemistry A, 115 (40). pp. 11016-11022. ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20111031-081704200

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Abstract

The practical levels of density functional theory (DFT) for solids (LDA, PBE, PW91, B3LYP) are well-known not to account adequately for the London dispersion (van der Waals attraction) so important in molecular solids, leading to equilibrium volumes for molecular crystals ∼10-15% too high. The ReaxFF reactive force field is based on fitting such DFT calculations and suffers from the same problem. In the paper we extend ReaxFF by adding a London dispersion term with a form such that it has low gradients (lg) at valence distances leaving the already optimized valence interactions intact but behaves as 1/R^6 for large distances. We derive here these lg corrections to ReaxFF based on the experimental crystal structure data for graphite, polyethylene (PE), carbon dioxide, and nitrogen and for energetic materials: hexahydro-1,3,5-trinitro- 1,3,5-s-triazine (RDX), pentaerythritol tetranitrate (PETN), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), and nitromethane (NM). After this dispersion correction the average error of predicted equilibrium volumes decreases from 18.5 to 4.2% for the above systems. We find that the calculated crystal structures and equation of state with ReaxFF-lg are in good agreement with experimental results. In particular, we examined the phase transition between α-RDX and γ-RDX, finding that ReaxFF-lg leads to excellent agreement for both the pressure and volume of this transition occurring at ∼4.8 GPa and ∼2.18 g/cm^3 density from ReaxFF-lg vs 3.9 GPa and ∼2.21 g/cm^3 from experiment. We expect ReaxFF-lg to improve the descriptions of the phase diagrams for other energetic materials.


Item Type:Article
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http://dx.doi.org/10.1021/jp201599t DOIArticle
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ORCID:
AuthorORCID
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2011 American Chemical Society. Received: February 17, 2011. Revised: August 22, 2011. Publication Date (Web): September 2, 2011. Financial support from the National Science Foundation of China (No. 20473052), NSAF funding (No. 10676021), and the National Basic Research Program of China (Nos. 2003CB615804 and 2007CB209701) is gratefully acknowledged. We acknowledge the funding from the China Scholarship Council (No. 2009623057, Cliff Bedford). In addition, we acknowledge Funding ONR (N00014-09-1-0634), ARO-MURI (W911NF-08-1-0124, Ralph Anthenien), and ARL HPC (with help from Betsy Rice).
Funders:
Funding AgencyGrant Number
National Science Foundation of China20473052
NSAF10676021
National Basic Research Program of China2003CB615804
National Basic Research Program of China2007CB209701
China Scholarship Council2009623057
Office of Naval Research (ONR)N00014-09-1-0634
Army Research Office (ARO)W911NF-08-1-0124
ARL HPCUNSPECIFIED
Issue or Number:40
Record Number:CaltechAUTHORS:20111031-081704200
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20111031-081704200
Official Citation:ReaxFF-lg: Correction of the ReaxFF Reactive Force Field for London Dispersion, with Applications to the Equations of State for Energetic Materials Lianchi Liu, Yi Liu, Sergey V. Zybin, Huai Sun, and William A. Goddard III The Journal of Physical Chemistry A 2011 115 (40), 11016-11022
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27509
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:01 Nov 2011 17:08
Last Modified:03 Oct 2019 03:24

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