Ground state of a spin-crossover molecule calculated by diffusion Monte Carlo
Citation:
A. Droghetti, D. Alf? and S. Sanvito, Ground state of a spin-crossover molecule calculated by diffusion Monte Carlo, Physics Review B, 87, 20, 2013, 205114-Download Item:
Abstract:
Spin-crossover molecules have recently emerged as a family of compounds potentially useful for implementing
molecular spintronics devices. The calculations of the electronic properties of such molecules is a formidable
theoretical challenge, as one has to describe the spin ground state of a transition metal as the ligand field changes.
The problem is dominated by the interplay between strong electron correlation at the transition-metal site and
charge delocalization over the ligands, and thus it fits into a class of problems where density functional theory
may be inadequate. Furthermore, the crossover activity is extremely sensitive to environmental conditions, which
are difficult to fully characterize. Here we discuss the phase transition of a prototypical spin-crossover molecule
as obtained with diffusion Monte Carlo simulations. We demonstrate that the ground state changes depending on
whether the molecule is in the gas or in the solid phase. As our calculation provides a solid benchmark for the
theory, we then assess the performances of density functional theory. We find that the low-spin state is always
overstabilized, not only by the (semi-)local functionals, but even by the most commonly used hybrids (such as
B3LYP and PBE0). We then propose that reliable results can be obtained by using hybrid functionals containing
about 50% of exact exchange
Sponsor
Grant Number
European Union (EU)
200150
Author's Homepage:
http://people.tcd.ie/sanvitoshttp://people.tcd.ie/droghea
Description:
PUBLISHED
Author: Sanvito, Stefano; Droghetti, Andrea
Sponsor:
European Union (EU)Type of material:
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Series/Report no:
Physics Review B87
20
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PhysicsSubject (TCD):
Nanoscience & MaterialsDOI:
http://dx.doi.org10.1103/PhysRevB.87.205114Metadata
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