Title

Anomalously Soft and Stiff Modes of Transition-Metal Nanoparticles

Authors

Authors

M. A. Ortigoza; R. Heid; K. P. Bohnen;T. S. Rahman

Comments

Authors: contact us about adding a copy of your work at STARS@ucf.edu

Abbreviated Journal Title

J. Phys. Chem. C

Keywords

TOTAL-ENERGY CALCULATIONS; VIBRATIONAL DYNAMICS; NONRADIAL OSCILLATIONS; MOLECULAR-DYNAMICS; LATTICE-VIBRATIONS; LINEAR-RESPONSE; SURFACE MODES; STARS; SIZE; NANOCRYSTALS; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, ; Multidisciplinary

Abstract

We propose an explanation for the enhanced low- and high-energy tails of the vibrational density of states (VDOS) of nanoparticles (NPs) with respect to their bulk counterparts. Density functional theory calculations of the frequency and eigenvector of each mode allow us to identify radial breathing/multipolar and nonraclial tidal/shear/torsional vibrations as the modes that populate such tails. These modes have long been obtained from elasticity theory and are thus analogous to the widely studied and observed pulsations in variable stars. The features particular to the VDOS of NPs are rationalized in terms of the charge density distribution around low-coordinated atoms, the quasi-radial geometric distribution of NPs, force constant variations, degree of symmetry of the nanoparticle, discreteness of the spectrum, and the confinement of the eigenmodes. Our results indicate that the high- and low-energy tails of the VDOS may be a powerful tool to reveal information about the chemical composition and geometric structure of small NPs. In particular, the size of the confinement gap at the low-frequency end of the VDOS and the extent by which the high-frequency end surpasses the bulk limit signal whether a NP is bulk-like or non-bulk-like and the extent to which it is disordered.

Journal Title

Journal of Physical Chemistry C

Volume

118

Issue/Number

19

Publication Date

1-1-2014

Document Type

Article

Language

English

First Page

10335

Last Page

10347

WOS Identifier

WOS:000336198900056

ISSN

1932-7447

Share

COinS