研究目的
To quantitatively characterize the intermolecular and intramolecular couplings that modulate the OH-stretch vibrational band in liquid water and to model the infrared (IR) spectra of various isotopic water solutions with different levels of vibrational couplings.
研究成果
The study provides direct evidence for the partially quantum-mechanical nature of hydrogen bonds in liquid water and quantitatively demonstrates that Fermi resonances are responsible for the shoulder at ～3250 cm?1 of the IR OH-stretch band of neat H2O.
研究不足
The study slightly underestimates the H-bond strength in liquid water, resulting in OH stretching frequencies that are approximately 57 cm?1 blue-shifted compared to experiment. The CMD band lacks intensity between 3000 cm?1 and 3300 cm?1.
1：Experimental Design and Method Selection:
The study combines the centroid molecular dynamics (CMD) formalism with the MB-pol potential energy function to model the IR spectra of isotopic water solutions.
2：Sample Selection and Data Sources:
Four isotopic solutions (neat H2O, diluted HOD in H2O, diluted H2O in D2O, and diluted HOD in D2O) are investigated.
3：List of Experimental Equipment and Materials:
CMD simulations are performed with MB-pol, a many-body potential energy function for water.
4：Experimental Procedures and Operational Workflow:
CMD simulations account for nuclear quantum effects, with each atom represented by a Feynman’s ring-polymer discretized with 32 beads.
5：Data Analysis Methods:
IR spectra are calculated within the time-dependent formalism, and local mode and local monomer calculations are performed to quantify Fermi resonance contributions.
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