Open AccessMolecular dynamics simulation of the rotational viscosity and its odd-even effect of nematic liquid crystals nCB(4-n-alkyl-4′-cyanobiphenyls, n=5—8)
Author(s) -
Ran Zhang,
Jun He,
Zenghui Peng,
Xuan Li
Publication year - 2009
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.58.5560
Subject(s) - molecular dynamics , rotational viscosity , exponential function , liquid crystal , viscosity , thermodynamics , isobaric process , correlation function (quantum field theory) , physics , alkyl , isothermal process , rotational diffusion , materials science , chemistry , condensed matter physics , molecule , mathematics , mathematical analysis , dielectric , quantum mechanics , organic chemistry
Based on a full-atomic force field model, molecular dynamics MD studies of nCB serials4-n-alkyl-4′-cyanobiphenyls, n=5—8were performed under the isothermal-isobaric NPT ensemble. The second and forth rank order parameters and the orientational time correlation function TCF were obtained by analyzing the trajectory of MD simulation. Then the correlation time was obtained from the fitting of TCF by a single exponential approximation and the rotational diffusion coefficient RDC was computed. The rotational viscosity coefficients RVC of nCBn=5—8 were calculated by Nemtsov-Zakharov and Fialkowski equations, which are based on the statistical-mechanical approach. The odd-even effect of RVC, RDC and the correlation time were discussed separately. Reasonable agreement between the calculated results and the measured data published in literature is obtained, including identical odd-even effect.