Infrared signature of micro-hydration in the organophosphate sarin [electronic resource] : An ab initio study
- Fort Belvoir, VA : United States. Defense Threat Reduction Agency, 2015. and Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- 17 pages : digital, PDF file
- Additional Creators:
- Sandia National Laboratories, United States. Defense Threat Reduction Agency, and United States. Department of Energy. Office of Scientific and Technical Information
- Restrictions on Access:
- Free-to-read Unrestricted online access
- The infrared (IR) spectra of micro-hydrated Sarin•(H<sub>2</sub>O)<sub>n</sub> clusters containing between one and four explicit waters have been studied using <i>ab initio</i> density functional theory (DFT) methods. The phosphate group P=O bond vibration region (~1270 to 1290 cm<sup>–1</sup>) revealed the largest frequency variation with hydration, with a frequency red shift reflecting the direct hydrogen bond formation between the P=O of Sarin and water. Small variations to the P-F stretch (~810 to 815 cm<sup>–1</sup>) and the C-O-P vibrational modes (~995 to 1004 cm<sup>–1</sup>) showed that the water interactions with these functional groups were minor, and that the structures of Sarin were not extensively perturbed in the hydrated complexes. Increasing the number of explicit hydration waters produced only small vibrational changes in the lowest free energy complexes. These minor changes were consistent with a single water-phosphate hydrogen bond being the dominant structure, though a second water-phosphate hydrogen bond was observed in some complexes and was identified by an additional red shift of the P=O bond vibration. As a result, the H<sub>2</sub>O•H<sub>2</sub>O vibrational modes (~3450 to 3660 cm<sup>–1</sup>) increased in complexity with higher hydration levels and reflect the extended hydrogen bonding networks formed between the explicit waters in the hydrated Sarin clusters.
- Published through SciTech Connect., 06/28/2015., "sand--2015-1636j", "567435", Journal of Molecular Modeling 21 7 ISSN 1610-2940 AM, and Todd M. Alam; Charles Joseph Pearce.
- Funding Information:
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