Resolution of the velocity autocorrelation function in fluids at various density states

Autor:	Yoshikazu Endo, Naofumi Ogita, Homare Endo
Rok vydání:	1982
Předmět:	Superposition principle Classical mechanics Autoregressive model Chemistry Low temperature combustion Autocorrelation Spectrum (functional analysis) Resolution (electron density) Mode (statistics) General Physics and Astronomy Intermediate region Physical and Theoretical Chemistry Atomic physics
Zdroj:	The Journal of Chemical Physics. 77:5184-5190
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.443695
Popis:	The purpose of this paper is to study the atomic motions of fluids at various density states by finding out the basic modes which construct the velocity autocorrelation function (VAF). For this purpose the VAF in a soft‐core system is calculated for the various density states ranging from a dilute gas to a dense liquid. Then the VAF’s are resolved into the Langevin and damped oscillatory modes by the use of an autoregressive (AR) analysis. The merits of the AR resolution is that the VAF’s can be easily resolved into the modes in an analytically expressed form. According to the respective role played by the Langevin modes and the damped oscillatory modes in the VAF and in its spectrum, three cases can be distinguished: (i) gaslike region which consists of one Langevin mode; (ii) intermediate region which consists of a superposition of one Langevin mode and more than one damped oscillatory modes; (iii) liquidlike region which consists of more than two damped oscillatory modes.
Databáze:	OpenAIRE
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