Dipole orientation and surface cluster size effects on chemisorption- induced magnetism: A DFT study of the interaction of gold-thiopolypeptide

Luis Puerta, Héctor J. Franco, Juan Murgich, Carlos Gonzalez, Yamil Simón-Manso, Vladimiro Mujica

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A nanosystem formed by a high electric dipole moment thiopolypeptide α-helix, consisting of eight L-glycine units, chemisorbed on the (111) surface of Au23 and Au55 clusters, with the S as the linking atom, was studied using the wave function broken symmetry UDFT method. We have found a strong correlation between the orientation of the electric dipole of the α-helix and charge transfer and the magnetic behavior of the adsorbate-cluster system. Upon chemisorption, dipole moments may be quenched or enhanced, with respect to the gas phase value, with the strongest reduction corresponding to the magnetic state. A reduction of the α-helix's electric dipole with the net charge transfer from the Au surface was obtained for the more stable state. In this state description, it may happen that the calculated spin densities of the chemisorbed α-helix and its free radical form are similar. The magnetic properties are strongly dependent on the size of the Au cluster and on its electronic structure with respect to nuclei positions. In general, the localized spin density per atom increases and the magnetization of the extended system decreases with cluster size, a trend found experimentally for organic monolayers with a similar type of adsorbate we consider here.

Original languageEnglish
Pages (from-to)9771-9783
Number of pages13
JournalJournal of Physical Chemistry A
Volume112
Issue number40
DOIs
Publication statusPublished - Oct 9 2008

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Magnetism
Adsorbates
Chemisorption
Discrete Fourier transforms
Gold
helices
chemisorption
Charge transfer
Electric dipole moments
electric dipoles
gold
dipoles
Nanosystems
Atoms
Dipole moment
Wave functions
Glycine
Free Radicals
Electronic structure
Monolayers

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Dipole orientation and surface cluster size effects on chemisorption- induced magnetism : A DFT study of the interaction of gold-thiopolypeptide. / Puerta, Luis; Franco, Héctor J.; Murgich, Juan; Gonzalez, Carlos; Simón-Manso, Yamil; Mujica, Vladimiro.

In: Journal of Physical Chemistry A, Vol. 112, No. 40, 09.10.2008, p. 9771-9783.

Research output: Contribution to journalArticle

Puerta, Luis ; Franco, Héctor J. ; Murgich, Juan ; Gonzalez, Carlos ; Simón-Manso, Yamil ; Mujica, Vladimiro. / Dipole orientation and surface cluster size effects on chemisorption- induced magnetism : A DFT study of the interaction of gold-thiopolypeptide. In: Journal of Physical Chemistry A. 2008 ; Vol. 112, No. 40. pp. 9771-9783.
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