Structural Models for Supercooled Liquids

2 Structural Models for Supercooled Liquids. - This approach focuses on the molecular order in the supercooled liquid. The potential energy surface or landscape I (r ) where = n, 2. .. is a 3A-dimensional vector in phase space has a characteristic appearance in the various states of matter. In a liquid, the 4 -landscape has a distribution of many shallow energy minima. In a crystal there are a few steep and deep minima representing the collapse of the system into the crystalline states with long-range order. In a liquid simulation, each of these deep minima, or inherent structures as they are called, will be surromided 

Oligschleger and Schober also investigated the intermittent diffusion processes in supercooled liquids. They generated a glass using a modified soft-sphere potential. 

Another perspective on the time-dependent microstructural evolution in supercooled liquids was presented by a new resolution of the radial distribution function. The concept of neighbourship was invented by Keyes. The g(r) was resolved into a series of separate radial distributions for the first neighbour, second neighbour and so on. As the temperature decreased it was found that these shells became more radially separated and that the dynamics of the first shell departed from a simple diflusive model, which is indicative of the onset of slow collective cluster dynamics.  

For an A-particle system at a given temperature, T, one chooses a configuration comprising a 3A-dimensional vector of atomic co-ordinates, Ra. The total potential is expanded as a Taylor series about Rt.  

Standard normal mode analysis of the matrix K is not necessarily positive definite, since the system is chosen from the trajectory of a system at non-zero temperature. Also F is also not necessarily zero. DiagonaUsation of K jdelds the 

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