Dresden 2017 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Posters - Statistical Physics, Stochastic Thermodynamics

DY 26.3: Poster

Dienstag, 21. März 2017, 18:15–21:00, P3

Determination of elastic constants in the isothermal-isobaric ensemble — •Dominik Lips and Philipp Maass — Universität Osnabrück, Fachbereich Physik, Barbarastraße 7, 49076 Osnabrück, Germany

The calculation of local elastic constants in heterogeneous materials from computer simulations is an important task for applications in materials science on the nanoscale and for a better understanding of biological processes involving elastic deformations. By combining Irving and Kirkwood’s definition of a continuum stress field in terms of averages over phase space functions [1], and the work of Ray and Rahman on the calculation of bulk elastic constants by equilibrium stress fluctuations [2], Lutsko succeeded to derive a stress fluctuation formula to cope with the problem of local elastic constants in heterogeneous materials [3]. This approach has been worked out in the canonical ensemble and cannot be applied in constant pressure simulations, as they are nowadays often conducted in soft matter and biological systems. We present new stress fluctuation formulas valid in the isothermal-isobaric ensemble, for both local and bulk elastic constants [4]. Useful applications of these fluctuation formulas to complex heterogeneous soft matter systems subject to external pressure will be discussed.

[1] J. H. Irving and J. G. Kirkwood, J. Chem. Phys. 18, 817 (1950).

[2] J. R. Ray and A. Rahman, J. Chem. Phys. 80, 4424 (1984).

[3] J. F. Lutsko, J. Appl. Phys. 64, 1152 (1988).

[4] D. Lips and P. Maass, preprint.