Self-Assembly of Glycine on Cu (001): The tale of Temperature and Polarity

Glycine on Cu(001) is used as an example to illustrate the critical role of molecular polarity and finite temperature effect in self-assembly of bio-molecules at a metal surface. A unified picture for glycine self-assembly on Cu(001) is derived based on full polarity compensation considerations. Temperature plays a non-trivial role: the ground-state structure at 0 K is absent at room temperature, where intermolecular hydrogen bonding overweighs competing molecule-substrate interactions. The unique p(2×4) structure predicted as the most stable structure was confirmed by ab initio molecular dynamics simulations, whose scanning tunneling microscopy images and anisotropic free-electron-like dispersion are in excellent agreement with experiments. Moreover, the rich self-assembling patterns including the heterochiral and homochiral phases, and their interrelationships are entirely governed by the same mechanism.