Browsing by Author "Tsay, SF"

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Instantaneous normal mode analysis of liquid Na
(1996-11-22)
Wu, TM
;
Tsay, SF
;
物理研究所
;
Institute of Physics
The instantaneous-normal-mode (INM) densities of states for liquid Na in four realistic thermodynamic states are obtained by molecular-dynamics simulation. The exponent functions derived from the INM densities of states are found to fit well with a binomial of frequency for the imaginary-frequency lobe and a three-term polynomial for the real-frequency lobe. Through the study of the size dependence for the participation ratios of INMs, we show that for both the real-frequency and the imaginary-frequency lobes, INMs of low frequencies are extended modes and INMs in the high-frequency end are localized modes. However, each lobe has a broad transition region in frequency from the extended to localized INMs. (C) 1996 American Institute of Physics.
Instantaneous normal mode analysis of liquid Na
(1996-11-22)
Wu, TM
;
Tsay, SF
;
物理研究所
;
Institute of Physics
The instantaneous-normal-mode (INM) densities of states for liquid Na in four realistic thermodynamic states are obtained by molecular-dynamics simulation. The exponent functions derived from the INM densities of states are found to fit well with a binomial of frequency for the imaginary-frequency lobe and a three-term polynomial for the real-frequency lobe. Through the study of the size dependence for the participation ratios of INMs, we show that for both the real-frequency and the imaginary-frequency lobes, INMs of low frequencies are extended modes and INMs in the high-frequency end are localized modes. However, each lobe has a broad transition region in frequency from the extended to localized INMs. (C) 1996 American Institute of Physics.
Instantaneous resonant modes in high-temperature gallium liquids
(2001-08-01)
Wu, TM
;
Tsay, SF
;
Chang, SL
;
Ma, WJ
;
物理研究所
We have studied the low-frequency, quasilocalized vibrational excitations in Ga liquids in terms of instantaneous-normal-mode analysis. We present strong numerical evidence for the existence of the instantaneous resonant modes (IRM's) in high-temperature Ga liquids. It is the exotic repulsive-core interaction between Ga particles that gives rise to the IRM's, which are associated with special local structures created by density fluctuation. In general, the IRM density of states is found to increase with temperature.
Local geometric structures of instantaneous resonant modes in Ga liquids
(2002-05-01)
Wu, TM
;
Ma, WJ
;
Chang, SL
;
Tsay, SF
;
物理研究所
Recently, we have numerically found the instantaneous resonant modes (IRMs) in high-temperature Ga liquids. The occurrence of these IRMs is attributed to the cooperation of the exotic repulsive core of the Ga pseudopotential and the local volume expansion. In this paper, the local structures around the quasilocalized centers of these IRMs are analyzed. (C) 2002 Elsevier Science B.V. All rights reserved.
Localized instantaneous normal modes in liquid Na
(1997)
Wu, TM
;
Tsay, SF
;
物理研究所
;
Institute of Physics
The instantaneous-normal-mode (INM) densities of states for liquid Na in four realistic thermodynamic states are obtained by molecular-dynamic simulation. Through the study of the size dependence for the average number of the excited particles in an INM, rye show that the INMs in the high-frequency end of each lobe are localized modes. By examining the projection components of the eigenvector of a localized INM on each particle, we show that the localized INM indeed has only one excited center at the particle with the largest projection component and the spatial size of the localization extends to the first nearest neighbor shell from the central particle. We also give a scenario of how a localized INM becomes an extended INM as the frequency decreases.