Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2008-10-30
J. Chem. Phys. 130, 104508 (2009)
Physics
Condensed Matter
Strongly Correlated Electrons
13 pages, 6 figures, also see animations at http://www.youtube.com/watch?v=3K2kP8hWpZI, http://www.youtube.com/watch?v=wIz1c
Scientific paper
10.1063/1.3080543
We calculate the effective Coulomb repulsion between electrons/holes, U, and site energy for an isolated BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene] molecule in vacuo. U=4.2 \pm 0.1 eV for 44 experimental geometries taken from a broad range of conformations, polymorphs, anions, temperatures, and pressures (the quoted `error' is one standard deviation). Hence we conclude that U is essentially the same for all of the compounds studied. This shows that the strong (hydrostatic and chemical) pressure dependence observed in the phase diagrams of the BEDT-TTF salts is not due to U. Therefore, if the Hubbard model is sufficient to describe the phase diagram of the BEDT-TTF salts there must be significant pressure dependence on the intramolecular terms in the Hamiltonian and/or the reduction of the Hubbard U due to the interaction of the molecule with the polarisable crystal environment. The renormalised value of U is significantly smaller than the bare value of the Coulomb integral: F_0=5.2\pm0.1 eV across the same set of geometries, emphasising the importance of using the renormalised value of U. The site energy (for holes), xi=5.0\pm0.2 eV, varies only a little more than U across the same set of geometries. However, we argue that this plays a key role in understanding the role of disorder in ET salts in general and in explaining the difference between the beta_L and beta_H phases of beta-(BEDT-TTF)_2I_3 in particular.
Powell Ben J.
Scriven Edan
No associations
LandOfFree
Towards the parameterisation of the Hubbard model for salts of BEDT-TTF: A density functional study of isolated molecules does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Towards the parameterisation of the Hubbard model for salts of BEDT-TTF: A density functional study of isolated molecules, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Towards the parameterisation of the Hubbard model for salts of BEDT-TTF: A density functional study of isolated molecules will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-278732