On the mechanism of reorientational and structural relaxation in supercooled liquids: The role of border dynamics and cooperativity

@article{citeulike:1414541, abstract = {Molecular dynamics simulation and analysis based upon the many-body potential energy landscape (PEL) are employed to characterize single molecule reorientation and structural relaxation, and their interrelation, in deeply supercooled liquid CS2. The rotational mechanism changes from small-step Debye diffusion to sudden large angle reorientation (SLAR) as the temperature falls below the mode-coupling temperature Tc. The onset of SLAR is explained in terms of the PEL; it is an essential feature of low-T rotational dynamics, along with the related phenomena of dynamic heterogeneity and the bifurcation of slow and fast relaxation processes. A long trajectory in which the system is initially trapped in a low energy local minimum, and eventually escapes, is followed in detail, both on the PEL and in real space. During the trapped period, \"return\" dynamics occurs, always leading back to the trap. Structural relaxation is identified with irreversible escape to a new trap. These processes lead to weak and strong SLAR, respectively; strong SLAR is a clear signal of structural relaxation. Return dynamics involves small groups of two to four molecules, while a string-like structure composed of all the active groups participates in the escape. It is proposed that, rather than simple, nearly instantaneous, one-dimensional barrier crossings, relaxation involves activation of the system to the complex, multidimensional region on the borders of the basins of attraction of the minima for an extended period. \©2004 American Institute of Physics.}, author = {Kim, Joohyun and Keyes, T. }, citeulike-article-id = {1414541}, doi = {10.1063/1.1776553}, journal = {The Journal of Chemical Physics}, keywords = {simulation, structure, supercooled}, number = {9}, pages = {4237--4245}, posted-at = {2007-06-26 22:46:52}, priority = {2}, publisher = {AIP}, title = {On the mechanism of reorientational and structural relaxation in supercooled liquids: The role of border dynamics and cooperativity}, url = {http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal\&id=JCPSA6000121000009004237000001\&idtype=cvips\&gifs=yes}, volume = {121}, year = {2004} }

TY - JOUR ID - citeulike:1414541 L3 - citeulike-article-id:1414541 TI - On the mechanism of reorientational and structural relaxation in supercooled liquids: The role of border dynamics and cooperativity JF - The Journal of Chemical Physics VL - 121 IS - 9 SP - 4237 EP - 4245 PB - AIP N2 - Molecular dynamics simulation and analysis based upon the many-body potential energy landscape (PEL) are employed to characterize single molecule reorientation and structural relaxation, and their interrelation, in deeply supercooled liquid CS2. The rotational mechanism changes from small-step Debye diffusion to sudden large angle reorientation (SLAR) as the temperature falls below the mode-coupling temperature Tc. The onset of SLAR is explained in terms of the PEL; it is an essential feature of low-T rotational dynamics, along with the related phenomena of dynamic heterogeneity and the bifurcation of slow and fast relaxation processes. A long trajectory in which the system is initially trapped in a low energy local minimum, and eventually escapes, is followed in detail, both on the PEL and in real space. During the trapped period, "return" dynamics occurs, always leading back to the trap. Structural relaxation is identified with irreversible escape to a new trap. These processes lead to weak and strong SLAR, respectively; strong SLAR is a clear signal of structural relaxation. Return dynamics involves small groups of two to four molecules, while a string-like structure composed of all the active groups participates in the escape. It is proposed that, rather than simple, nearly instantaneous, one-dimensional barrier crossings, relaxation involves activation of the system to the complex, multidimensional region on the borders of the basins of attraction of the minima for an extended period. ©2004 American Institute of Physics. KW - simulation KW - structure KW - supercooled AU - Kim, Joohyun AU - Keyes, T PY - 2004/// UR - http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JCPSA6000121000009004237000001&idtype=cvips&gifs=yes ER -