The classical ground state of a flexible chain molecule (polymer) is well known to be simple, just a straight line. Here we consider quantum fluctuations of flexible chains. In their presence, the straight ground (zero-temperature) state becomes rough, whereas the Hookean, linear elastic theory breaks down: For a weak tensile force applied to the chain ends, the increment of the chain length is ~(force)1/2. In non-self-avoiding chains, quantum fluctuations alone may induce a zero-temperature phase transition from the straight to a crumpled ground state. Self-avoiding chains, however, appear to have only straight ground states. We discuss these phenomena in physical systems of interest for molecular nanotechnology.
展开▼
