The physics and chemistry of organic molecules adsorbed on metals is intensively investigated at present [1,2,3,4,5]. In this context, it was shown that glycine, adsorbed on Cu(110), forms heterochiral (3 x 2) reconstructed overlayers [6,7] in marked contrast to phenylglycine preferring the homochiral adsorption [5]. Density-functional theory within generalized gradient approximation is used to identify the origin of this puzzling difference. The bonding of glycine and phenylglycine on Cu(110) is analyzed in detail and predominantly explained in terms of covalent bonds. The striking difference in the bonding behavior of glycine and phenylglycine is found to be related to the restriction of the molecular relaxation imposed by the phenyl group in conjunction with intermolecular hydrogen bonds.
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[2] Q. Chen and N.V. Richardson, Nat. Mater. 2, 324 (2003).
[3] W. G. Schmidt, et al., Appl. Phys. A 85, 387 (2006).
[4] M. Preuss, W. G. Schmidt and F. Bechstedt, Phys. Rev. Lett. 94, 236102 (2005).
[5] S. Blankenburg and W. G. Schmidt, Phys Rev. B 74, 155419 (2006).
[6] R. L. Tomes, et al., Surf. Sci. 522, L9 (2003).
[7] R. B. Rankin and D. S. Sholl, Surf. Sci. 548, 301 (2003).
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