REAL-SPACE RENORMALIZATION-GROUP TECHNIQUE FOR LOW-LYING ENERGY-STATES IN CHAIN FOLDING

We apply a real-space renormalization-group (RG) technique to study th e low-lying energy states of a strongly interacting copolymer chain on a three-dimensional simple cubic lattice. The chain is 27 beads long and consists of randomly chosen hydrophobic and polar components where by the system favors interactions between similar beads. The RG scheme is applied by dividing the chain into different parts (conformons) an d applying a variety of boundary conditions to find the embedded confo rmons with the lowest energy. The conformations of the low-lying energ y states are found by combining the conformons of different parts of t he chain. We show that the 27 beads chain folds into a 3X3X3 cube for the lowest energy state. We also obtain conformations which do not fol d into a cube but have structural similarities to the lowest energy st ate. The model is static but can help to understand folding processes of polymeric molecules and can be extended to more complex situations. (C) 1998 American Institute of Physics.