Symmetrized projector quantum Monte Carlo studies of the ground state of $C_{60}$

Srinivasan, Bhargavi and Ramasesha, S and Krishnamurthy, HR (1996) Symmetrized projector quantum Monte Carlo studies of the ground state of $C_{60}$. In: Physical Review B, 54 (3). pp. 1692-1702.

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Abstract

We develop a symmetrized version of the projector quantum Monte Carlo SPQMC method which preserves the symmetries of the system by simultaneously sampling all symmetry-related Ising configurations at each MC step and use it to study the effect of electron correlations on a single $C_{60}$ molecule and its structural motifs, within the Hubbard model. This SPQMC method allows more accurate estimates of correlation functions as seen from calculations on small systems. The method applied to some molecular fragments of $C_{60}$ , viz., pyracylene, fluoranthene, and corannulene, gives a good chemical description of these systems. Analysis of the ground-state bond orders allows us to visualize pyracylene as a naphthalene moiety with weakly bridged ethylenic units, fluoranthene as weakly bridged naphthalene and benzene units, and corannulene as radialene with ethylenic bridges. We study the ground-state properties of a single fullerene molecule, with and without bond alternation. The bond orders in the ground state for the two types of nearest-neighbor bonds are unequal, even for uniform $C_{60}$ . The spin and charge correlations give a consistent picture of the interacting ground state in all these systems. We construct projections of the bond orders and spin-spin correlation functions on the space of irreducible representations of the icosahedral point group. These projections, analogous to the structure factors of translationally invariant systems, give the amplitudes for distortions which transform as the irreducible representations of the point group. The amplitude for the $H_g$ distortion is the largest, while the spin structure has large weights in the $T_{2g}$ and $G_u$ representations.

Item Type:	Journal Article
Publication:	Physical Review B
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit Division of Physical & Mathematical Sciences > Physics
Date Deposited:	27 Dec 2006
Last Modified:	19 Sep 2010 04:33
URI:	http://eprints.iisc.ac.in/id/eprint/9124

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