Extended concerted-rotation

Fig. 4a-c. Schematic of the three Extended Concerted-Rotation moves discussed in the text a ECROTl, h ECROT2, and c ECROT3. Beads lefnesented by fitted circles remain fixed in each move. Beads represented by empty cirdes are changed by random rotations of torsional angles. Shaded batds are moved by Concerted-Rotation... 

Table 3. Summary of results of runs performed for the detomination of the optimum Extended Concerted-Rotation method for a melt of C71 pc ybead molecules. The maximum step size for randomly turned angles was 5 that for CONROT driver angles was 10"...

Simulation techniques for on- or off-lattice systems are, in general, applicable to systems with different degrees of coarsening. Their effectiveness, however, is often model-specific. In the following sections we describe different types of moves some of them can be applied to almost any type of molecular model (e.g., reptation, configurational-bias), and some others are applicable only to certain types of models (e.g., extended configurational bias or concerted-rotations). 

Figure 1. Illustration of the principle of operation of various elementary Monte Carlo moves from top to bottom single-site displacement moves, reptation moves, Continuum configurational-bias move, Extended continuum configurational-bias (ECCB) moves and also concerted-rotation moves (CONROT), and end-bridge moves.

Our results from oif-lattice simulations of dense polymer phases, obtained with a combination of newly available simulation tools, demonstrate that the Concerted-Rotation MC algorithm, introduced recently by Dodd et al. [47], is a valuable tool for the simulation of realistic polymer modds. While CONROT does not constitute an improvement over existing methods for systems with many chain ends, CONROT-based algorithms considerably extend the ran trf systems and problems that can be studied with MC methods. Such algorithms are particularly powerful when the >lutions to the geometric CONROT problem are selected with bias. 

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