Document Detail


Computer simulation study of thermodynamic scaling of dynamics of 2Ca(NO(3))(2)[middle dot]3KNO(3).
MedLine Citation:
PMID:  22047255     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Molecular dynamics (MD) simulations of the glass-former 2Ca(NO(3))(2)[middle dot]3KNO(3), CKN, were performed as a function of temperature at pressures 0.1 MPa, 0.5 GPa, 1.0 GPa, and 2.0 GPa. Diffusion coefficient, relaxation time of the intermediate scattering function, and anion reorientational time were obtained as a function of temperature and densitiy ρ. These dynamical properties of CKN scale as ρ(γ)∕T with a common value γ = 1.8 ± 0.1. The scaling parameter γ is consistent with the exponent of the repulsive part of an effective intermolecular potential for the repulsion between the atoms at shortest distance in the equilibrium structure of liquid CKN, Ca(2+), and oxygen atoms of NO(3) (-). Correlation between potential energy and virial is obeyed for the short-range terms of the potential function, but not for the whole potential including coulombic interactions. Decoupling of diffusion coefficient and reorientational relaxation time from relaxation time take place at a given ρ(γ)∕T value, i.e., breakdown of Stokes-Einstein and Debye-Stokes-Einstein equations result from combined thermal and volume effects. The MD results agree with correlations proposed between long-time relaxation and short-time dynamics, lnτ ∝ 1∕〈u(2)〉, where the mean square displacement 〈u(2)〉 concerns a time window of 10.0 ps. It has been found that 〈u(2)〉 scales as ρ(γ)∕T above and below the glass transition temperature, so that thermodynamic scaling of liquid dynamics can be thought as a consequence of theories relating short- and long-time dynamics, and the more fundamental scaling concerns short-time dynamical properties.
Authors:
Mauro C C Ribeiro; Tullio Scopigno; Giancarlo Ruocco
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of chemical physics     Volume:  135     ISSN:  1089-7690     ISO Abbreviation:  J Chem Phys     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-11-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375360     Medline TA:  J Chem Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  164510     Citation Subset:  IM    
Affiliation:
Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, C.P. 26077, 05513-970, São Paulo, SP, BrazilIstituto Nazionale per la Física della Materia and Dipartimento di Fisica, Universitá di Roma La Sapienza, 00185 Roma, Italy.
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