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Muhammad M Siddick

Publications and source records attributed to Muhammad M Siddick.

3 recordsLinked to original sources
PubMed2005

Toward understanding mobile proton behavior from first principles calculation: the short hydrogen bond in crystalline urea-phosphoric acid.

The dynamics of the intermolecular short hydrogen bond in the molecular complex of urea and phosphoric acid are investigated using plane-wave density functional theory. Results indicate migration of the proton toward the center of the hydrogen bond as temperature is increased, in line with recent experimental measurements. Computed vibrational frequencies show favorable agreement with experimental measurement. An analysis of existing neutron diffraction data leads us to conclude that the effective potential well experienced by the proton is temperature-dependent. Inspired by our computations and theoretical analysis, we offer a possible explanation for the proton migration phenomenon.

Journal Article↗
PubMed2003

Determining the strengths of hydrogen bonds in solid-state ammonia and urea: insight from periodic DFT calculations.

Plane-wave density functional theory has been applied to determine the strengths of hydrogen bonds in the phase I crystal structures of ammonia and urea. For ammonia, each component of the trifurcated hydrogen bond has been found to be almost as strong as a standard N-H.N interaction, and for urea the strengths of the two different N-H.O interactions have been determined by a quantum mechanical technique for the first time.

Ammonia↗