Self-assembly of glycine on Cu(001): the effect of temperature and polarity

Abstract

Self-assembly (SA) of molecules on solid surfaces has attracted enormous attention in terms of fundamental interest and a variety of applications. Here glycine on Cu(001) is studied as an example to illustrate the critical role of finite temperature and molecular polarity in the SA of biomolecules at a metal surface. We clarify that the SA structure of a glycine monolayer on Cu(001) is thermodynamically stable as determined by the lowest energy at room temperature, and a p(2 × 4) structure is identified to be the most stable through ab initio molecular dynamics simulations. This unique p(2 × 4) structure is derived based on a full polarity compensation mechanism, and its STM 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 inter-relationships are found to be entirely governed by the same polarity compensation mechanism.