Premium
Rationalization of the behavior of M 2 (CH 3 CS 2 ) 4 I (M = Ni, Pt) chains at room temperature from periodic density functional theory and ab initio cluster calculations
Author(s) -
Tabookht Zahra,
López Xavier,
de Graaf Coen,
Guihéry Nathalie,
Suaud Nicolas,
Benamor Nadia
Publication year - 2012
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23009
Subject(s) - delocalized electron , chemistry , density functional theory , density of states , fermi level , ab initio , dimer , band gap , electronic structure , electron localization function , crystallography , condensed matter physics , computational chemistry , electron , physics , organic chemistry , quantum mechanics
Abstract The electrical conductivities and plausible charge‐ordering states in the room temperature (r.t.) phase for MMX chains [Ni 2 (dta) 4 I] ∞ and [Pt 2 (dta) 4 I] ∞ (dta = CH 3 CS 2 − ) have been analyzed with periodic density functional theory (DFT) and correlated ab initio calculations combined with the effective Hamiltonian theory. Periodic DFT calculations show a more delocalized nature of the ground state in [Pt 2 (dta) 4 I] ∞ compared to [Ni 2 (dta) 4 I] ∞ , which features a rather large energy gap between the occupied and empty bands, and charge polarized dimer units. A larger electrical conductivity for the Pt chain can be expected, especially because the Fermi level lies within a band with contributions from Pt and I orbitals. Electronic structure parameters extracted from ab initio cluster calculations show that the large difference between the observed conductivities at 300 K for Ni and Pt compounds, of 3 orders of magnitude, cannot be explained from the parameters extracted from an embedded M 2 (dta) 4 I 2 dimer fragment alone. When tetramer fragments are considered, we observe that the interdimer transfer integral ( t ) between neighboring M 2 units connected by an iodine atom at correlated level is comparable in both chains. On the other hand, the energy to transfer an electron from a dimer to the neighboring one (Coulomb repulsion U ) is three times larger in the Ni compound with respect to the Pt chain, in line with the poor conductivity of the former. The electronic structure of the M 4 (dta) 8 I 3 fragment points to an alternate charge‐polarization state for Ni and an average valence state for Pt when the r.t. X‐ray structure is considered. © 2012 Wiley Periodicals, Inc.