First-Principles Study on Ligand Binding and Positional Disorder in Pentlandite

Calum N. Waterson, Julien O. Sindt, Jun Cheng, Peter A. Tasker, Carole A. Morrison*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Density functional theory, in conjunction with a cluster expansion model, has been used to study the structure and stability of the positionally disordered iron-nickel sulfide mineral pentlandite (Pn), (Fe,Ni)9S8, with results indicating heterogeneous nearest neighbor metal contacts are more energetically favorable than homogeneous contacts. The virtual crystal approximation was also explored as a means to address positional disorder, but while reliable results could be obtained for the bulk model, the same was not true for the surface, as local distortions which affected the surface model energies could not be reproduced. We also address the binding of ethyl xanthate (CH3CH2OCS2 -), water, and hydroxide to the [111] Pn surface to understand the mode of action of industrial xanthate flotation agents better. In order to model anionic ligands bound to a periodic boundary condition surface we propose applying a correction derived from the surface work function to remove the additional charge introduced by the ligand. The results obtained from the ligand binding studies indicate that while ethyl xanthate could readily displace up to a full monolayer of water per unit cell it is likely that Fe-enriched surfaces will bind xanthate in competition with the hydroxide anion, while a Ni-enriched surface will preferentially bind hydroxide anions over xanthate.

Original languageEnglish
Pages (from-to)25457-25468
Number of pages12
JournalThe Journal of Physical Chemistry C
Issue number45
Publication statusPublished - 14 Oct 2015

Bibliographical note

We acknowledge the UK Carr Parinello consortium for allocation of computing time on the ESPC high performance computing resource ARCHER (managed by the Edinburgh Parallel Computing Centre), the EaSTCHEM Research Computing Facility, and the University of Edinburgh ECDF facility. We also acknowledge advice from Dr. D. S. Middlemiss (Warwick University) and invaluable support from Drs. Farinato, Nagaraj, and Griffin at CYTEC industries Inc. as well as Drs. Shackleton, Malysiak, and Mr. De Vaux at Anglo American Plc., and to those companies for funding of a Ph.D. studentship for C.N.W. J. O. S. acknowledges the Engineering and Physical Sciences Research Council for the provision of a PhD. Studentship.


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