Quantum Effects in Hydrogen Bonded Liquids

Discretized path integral simulation methods, supplemented by a wavefunction-based representation, has been applied to the determination of aspects of the structure and spectroscopy in two quantum mechanical aqueous systems. The first of these applications is the determination of the consequences of quantizing the molecular degrees of freedom of the water molecules in the pure room temperature liquid. The results provide a quantitative estimate of the significance of approximating such a system as classical and also of the size of isotope effects on the liquid structure. The latter exhibit quantitative differences from recent experiments, indicating limitations in the model used for the solvent. Second, aspects of the structure and spectroscopy of the hydrated electron are considered. Here, we treat the water classically but treat the electron quantum mechanically. The excess electron density and solvent distribution are shown to exhibit structural similarities to ionic solvation. However, it is found that the electronic state fluctuates in response to the fluid, and that these fluctuations have essential consequences for the spectroscopy of the species. In both examples, the high frequency librational motions, and the associated fluctuating fields, that are manifestations of the light hydrogen mass, polarity, and strong restoring forces characteristic of molecular displacements in hydrogen bonded liquids are found to be key ingredients in the description of the phenomena.

[1]  U. Schindewolf.  Physical and Chemical Properties of Dissolved Electrons (Excess Electrons) , 1978 .

[2]  I. R. Mcdonald,et al.  Molecular dynamics studies of the structure of water at high temperatures and density , 1981 .

[3]  William L. Jorgensen,et al.  Energy component analysis for dilute aqueous solutions of lithium(1+), sodium(1+), fluoride(1-), and chloride(1-) ions , 1984 .

[4]  R. A. Kuharski,et al.  A quantum mechanical study of structure in liquid H2O and D2O , 1985 .

[5]  P. Rossky,et al.  The hydrated electron: quantum simulation of structure, spectroscopy, and dynamics , 1988 .

[6]  L. Kevan.  Electron spin echo studies of solvation structure , 1981 .

[7]  H. Berendsen,et al.  Interaction Models for Water in Relation to Protein Hydration , 1981 .

[8]  P. A. Egelstaff,et al.  Quantum effects in the structure of water measured by gamma ray diffraction , 1986 .

[9]  R. Impey,et al.  Study of electron solvation in polar solvents using path integral calculations , 1986 .

[10]  Roger Impey,et al.  Hydration and mobility of ions in solution , 1983 .

[11]  Walter Kauzmann,et al.  The Structure and Properties of Water , 1969 .

[12]  F. Stillinger,et al.  Improved simulation of liquid water by molecular dynamics , 1974 .

[13]  M. Mezei,et al.  Monte Carlo studies of the structure of dilute aqueous sclutions of Li+, Na+, K+, F−, and Cl− , 1981 .

[14]  P. Rossky,et al.  An electron–water pseudopotential for condensed phase simulation , 1987 .

[15]  P. Rossky,et al.  On the nature of pre-existing states for an excess electron in water , 1989 .

[16]  John C. Thompson.  Electrons in liquid ammonia , 1976 .

[17]  U. Landman,et al.  Electron localization in water clusters. I. Electron--water pseudopotential , 1988 .

[18]  W. L. Jorgensen,et al.  Comparison of simple potential functions for simulating liquid water , 1983 .

[19]  H. A. Levy,et al.  X-ray diffraction study of liquid water in the temperature range 4–200°C , 1967 .

[20]  L. Szász,et al.  Pseudopotential Theory for Atoms and Molecules , 1977 .

[21]  Aneesur Rahman,et al.  Hydrated electron revisited via the feynman path integral route , 1986 .

[22]  L. Kevan,et al.  Electron-solvent and anion-solvent interactions , 1976 .

[23]  F. Stillinger,et al.  Molecular Dynamics Study of Liquid Water , 1971 .

[24]  Joshua Jortner,et al.  Electrons in Fluids , 1973 .

[25]  F. Jou,et al.  Temperature and isotope effects on the shape of the optical absorption spectrum of solvated electrons in water , 1979 .

[26]  Anders Wallqvist,et al.  Path integral Monte Carlo study of the hydrated electron , 1987 .

[27]  Bruce J. Berne,et al.  On the Simulation of Quantum Systems: Path Integral Methods , 1986 .

[28]  Stuart A. Rice,et al.  Low-Energy Elastic Scattering of Electrons and Positrons from Helium Atoms , 1965 .

[29]  F. Gianturco,et al.  The scattering of slow electrons by polyatomic molecules. A model study for CH4, H2O and H2S , 1980 .

[30]  Schnitker,et al.  A priori calculation of the optical absorption spectrum of the hydrated electron. , 1988, Physical review letters.

[31]  B. Webster.  Chapter 10. Electron solvation phenomena , 1979 .

[32]  Sow-Hsin Chen,et al.  Isochoric temperature differential of the x-ray structure factor and structural rearrangements in low-temperature heavy water , 1983 .

[33]  J. Banavar,et al.  Computer Simulation of Liquids , 1988 .

[34]  E. Hart,et al.  The Hydrated Electron , 1963, Science.

[35]  L. Kevan,et al.  Theoretical models for solvated electrons , 1980 .