التفاصيل البيبلوغرافية
| العنوان: |
Molecular hydrodynamic theory of the velocity autocorrelation function. |
| المؤلفون: |
Seyler, S. L., Seyler, C. E. |
| المصدر: |
Journal of Chemical Physics; 8/7/2023, Vol. 159 Issue 5, p1-14, 14p |
| مصطلحات موضوعية: |
MOLECULAR theory, SUPERCRITICAL fluids, VELOCITY, POWER spectra, LIQUEFIED gases |
| مستخلص: |
The velocity autocorrelation function (VACF) encapsulates extensive information about a fluid's molecular-structural and hydrodynamic properties. We address the following fundamental question: How well can a purely hydrodynamic description recover the molecular features of a fluid as exhibited by the VACF? To this end, we formulate a bona fide hydrodynamic theory of the tagged-particle VACF for simple fluids. Our approach is distinguished from previous efforts in two key ways: collective hydrodynamic modes and tagged-particle self-motion are modeled by linear hydrodynamic equations; the fluid's spatial velocity power spectrum is identified as a necessary initial condition for the momentum current correlation. This formulation leads to a natural physical interpretation of the VACF as a superposition of products of quasinormal hydrodynamic modes weighted commensurately with the spatial velocity power spectrum, the latter of which appears to physically bridge continuum hydrodynamical behavior and discrete-particle kinetics. The methodology yields VACF calculations quantitatively on par with existing approaches for liquid noble gases and alkali metals. Furthermore, we obtain a new, hydrodynamic form of the self-intermediate scattering function whose description has been extended to low densities where the Schmidt number is of order unity; various calculations are performed for gaseous and supercritical argon to support the general validity of the theory. Excellent quantitative agreement is obtained with recent MD calculations for a dense supercritical Lennard-Jones fluid. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
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