Ab Initio Many-body Study of Cobalt Adatoms Adsorbed on Graphene

Abstract

Many recent calculations have been performed to study a Co atom adsorbed on graphene, with significantly varying results on the nature of the bonding. We use auxiliary-field quantum Monte Carlo (AFQMC) and a size-correction embedding scheme to accurately calculate the binding energy of Co on graphene. We find that as a function of the distance h between the Co atom and the six-fold hollow site, there are three distinct ground states corresponding to three electronic configurations of the Co atom. Two of these states provide binding and exhibit a double-well feature with nearly equal binding energy of 0.4 eV at h = 1.51 and h = 1.65 angstroms, corresponding to low-spin ${}^2$Co (3d9 4s0) and high-spin ${}^4$Co (3d8 4s1), respectively.

5 pages, 3 figures, 1 table. Submitted to Physical Review B

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• The Stability, Energetics, and Magnetic States of Cobalt Adatoms on Graphene
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• Error Cancellation in Diffusion Monte Carlo Calculations of Surface Chemistry
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