A comprehensive analysis of the elementary processes behind the scanning tunneling microscope controlled rotation of C2H2 and C2D2, isotopologues of a single acetylene molecule adsorbed on the Cu(001) surface is given, with a focus on the isotope effects. With the help of density-functional theory we calculate the vibrational modes of C2H2 and C2D2 on Cu(001) and estimate the anharmonic couplings between them, using a simple strings-on-rods model. The probability of the elementary processes -- non-linear and combination band -- are estimated using the Keldysh diagram technique. This allows us to clarify the main peculiarities and the isotope effects of the C2H2 and C2D2 on Cu(001) rotation, discovered in the pioneering work [Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)], which have not been previously understood.
@article{arxiv.1312.7113,
title = {Isotope effect in acetylene C$_2$H$_2$ and C$_2$D$_2$ rotations on Cu(001)},
author = {Yulia E. Shchadilova and Sergei G. Tikhodeev and Magnus Paulsson and Hiromu Ueba},
journal= {arXiv preprint arXiv:1312.7113},
year = {2014}
}
Comments
10 pages, 6 figures. Parts of this submission previously used in the supplementary materials section of arXiv:1307.7550