The diagonal bond method: A new lattice polymer model for simulation study of block copolymers A new lattice model for Monte Carlo simulations of dense polymer melts, developed in the spirit of VerdierStockmayer algorithm on square and simple cubic lattices, is presented. By introducing diagonals of squares and cubes as bonds, the lattice model acquires a large number of configurations and wiggling local moves. While it maintains the excluded volume interactions of monomers, it allows bond crossings and phantom moves, which result in a high mobility of polymers. For an application, we carry out simulations of symmetric AB block copolymer melts and observe a firstorder transition. We also show the stretching of the chains, namely, the nonGaussian character, as a function of temperature. A quicker evolution towards thermal equilibrium enables us to form an ordered tricontinuous doublediamond (OTDD) phase for linear ABC triblock copolymers and a new cylindrical phase for star ABC triblock copolymers. 
