Modeling of Chemical Warfare Agents

Quantum-Chemical Modeling of the Adsorption of Chemical Warfare Agents and Simulants

Dr. Victor Bermudez, victor.bermudez@nrl.navy.mil

There is a critical need for a quantitative understanding of the interaction of chemical warfare agents (CWA's) with materials. Experimental work with real agents is extremely dangerous and, therefore, costly and time-consuming. Furthermore, because of the hazards involved, such work can be done only in a small number of specially-designed facilities. Ab initio quantum-chemical modeling is being used to study (safely and relatively cheaply) the adsorption of both CWA's and CWA simulants on oxide materials (primarily Al₂O₃ and SiO₂). The goals are, first, to develop and test the necessary models. Secondly, the aim is to compare "side-by-side" the properties of simulants and real agents for the purpose of evaluating and improving the simulants. A third goal is a quantitative and microscopic understanding of how CWA's adsorb on prototypical oxides for the purpose of aiding in a "materials-by-design" approach to CWA detection, protection and remediation. Yet another objective is to evaluate the properties of "non-traditional" agents, i.e., modified versions of well-known CWA's. These are the CWA equivalents of "designer drugs", and quantum-chemical modeling allows such species to be studied before they have been synthesized or, worse yet, actually deployed.

Result of the ab initio quantum-chemical modeling of the adsoption of Sarin on a-SiO₂. The different elements are labeled and color-coded. Only a small section of the a-SiO₂ model is shown. The actual model used was much larger (Si₂₄O₄₈). The heave green lines show the hydrogen-bonding interaction between the O atom of the phosphonyl (P=O) group and two So-OII groups. The structure shown is the lowest in energy. Other structures involving H-bonding to the F atom or to the O atom in the C-O-P bond are less stable.

This work makes use mainly of the Gaussian, ADF and Crystal software suites operating on various DOD supercomputers accessed under the High-Performance Computing Modernization Program (HPCMP).

2011

• First-Principles Study of Adsorption of Dimethyl Methylphosphonate on TiO₂ Anatase (001) Surface: Formation of a Stable Titanyl (TidO) Site, Journal of Physical Chemistry C, 115, 6741 (2011).

2010

• Computational Study of the Adsorption of Dimethyl Methylphosphonate (DMMP) on the (010) Surface of Anatas TiO₂ With and Without Faceting, Surf.Sci. 604, 706 (2010)

2009

• Computational Study of Environmental Effects in the Adsorption of DMMP, Sarin and VX on γ-Al₂O₃ Surfaces: Hydrolysis and Photolysis, J. Phys. Chem. C. 113, 1917 (2009).

2008

• Energy-level alignment in the adsorption of phosphonyl reagents on γ-Al₂O₃, Surface Science 602, 1938 (2008).

2007

• Quantum-Chemical Study of the Adsorption of DMMP and Sarin on γ-Al₂O₃, J. Phys. Chem. C 111, 3719 (2007).
• Computational Study of the Adsorption of Trichlorophosphate, DMMP and Sarin on Amorphous SiO₂, J. Phys. Chem. C 111, 9314 (2007).

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