1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Assessment of density functional theory for iron(II) molecules across the spin-crossover transition
Rent:
Rent this article for
USD
10.1063/1.4752411
/content/aip/journal/jcp/137/12/10.1063/1.4752411
http://aip.metastore.ingenta.com/content/aip/journal/jcp/137/12/10.1063/1.4752411

Figures

Image of FIG. 1.
FIG. 1.

Energy level diagram for an octahedrally coordinated transition metal (TM) ion. In crystal field theory, the 3d orbitals of the TM ion have an energy split ΔCF due to the electrostatic interaction with the ligands. In contrast, in ligand field theory the 3d orbitals of the TM ion form covalent bonds with the ligands. In this diagram, we assume that each ligand contributes three p-orbitals, one with the positive lobe pointing toward the TM ion, σ-type, and two with the lobes perpendicular to it, π-type, (note that the σ- and π-type p orbitals are degenerate but here they are plotted slightly separated for better display). The π-type p orbitals couple with the TM t 2g states, while the σ-type p orbitals couple with the e g . Since the π interaction is weaker than the σ one, the antibonding t 2g π* orbitals lie lower in energy than the e g σ* ones. The energy splitting between the t 2g π* and the e g σ* orbitals is indicated by ΔLF + ΔCF.

Image of FIG. 2.
FIG. 2.

Potential energy surface of the HS and LS state of a SC molecule. The collective coordinate r represents all the 3N nuclear coordinates of the molecule. The zero-point phonon energies for the HS and LS state, and , the adiabatic energy gap, ΔE adia, and the vertical energy gaps, and are indicated.

Image of FIG. 3.
FIG. 3.

The cations investigated in this work [Fe(H2O)6]2+ (a), [Fe(NH3)6]2+ (b), [Fe(NCH)6]2+ (c), and [Fe(CO)6]2+ (d). Color code: C = yellow, O = red (small sphere), Fe = red (large sphere), N = grey, H = blue.

Image of FIG. 4.
FIG. 4.

Adiabatic energy gaps calculated with DFT and DMC. The DFT results were obtained with the functionals indicated in the legend and the basis set C. The DMC results were obtained for the structures optimized with B3LYP (basis set C) and with time-steps Δτ = 0.005 a.u. (the error bars are smaller than the symbols).

Image of FIG. 5.
FIG. 5.

Adiabatic energy gaps versus the fraction of HF exchange included in the hybrid functionals B3LYP and PBE0 for [Fe(NCH)6]2+ (upper panel) and [Fe(CO)6]2+ (lower panel). The basis set C was used.

Tables

Generic image for table
Table I.

Bond-lengths of [Fe(H2O)6]2+ in the HS and LS state, as calculated with various functionals and basis sets. Note that the LDA calculations for the HS state did not converge in the case of the basis sets B and C.

Generic image for table
Table II.

Adiabatic energy gap, ΔE adia, for the cation [Fe(H2O)6]2+. The functional and the basis set used for the each calculation are indicated.

Generic image for table
Table III.

Bond-lengths of [Fe(NH3)6]2+ in the HS and LS state, as calculated with various functionals and basis sets. Note that the LDA calculations for the HS state did not converge in the case of basis set B.

Generic image for table
Table IV.

Adiabatic energy gap, ΔE adia, for the cation [Fe(NH3)6]2+. The functional and the basis set used for each calculation are indicated.

Generic image for table
Table V.

Bond-lengths of [Fe(NCH)6]2+ in the HS and LS state as calculated with various functionals and for the basis set C.

Generic image for table
Table VI.

Adiabatic energy gap, ΔE adia, for the cation [Fe(NCH)6]2+ calculated with various functionals and the basis set C.

Generic image for table
Table VII.

Bond-lengths of [Fe(CO)6]2+ in the HS and LS state, as calculated with various functionals and for the basis set C.

Generic image for table
Table VIII.

Adiabatic energy gap, ΔE adia, for the cation [Fe(CO)6]2+ calculated with various functionals and the basis set C.

Generic image for table
Table IX.

Energy difference between the phonon zero point energy of the HS and LS state calculated with the various functionals employed in this work (only results for the basis set C are shown).

Generic image for table
Table X.

DMC total energy for the LS state, the HS state, and the adiabatic energy gap of the Fe(H2O)6]2+ ion. The molecular structures were optimized by DFT using the various functionals and basis sets listed in the first column. The time-steps chosen for the DMC simulation are also indicated. Differences in energy are well converged for Δτ = 0.005 a.u.

Generic image for table
Table XI.

DMC total energy for the LS state, the HS state, and the adiabatic energy gap of the [Fe(NH3)6]2+ ion. The molecular structures were optimized by DFT using the various functionals and basis sets listed in the first column. The time-steps chosen for the DMC simulation are also indicated. Differences in energy are well converged for Δτ = 0.005 a.u.

Generic image for table
Table XII.

DMC total energy for the LS state, the HS state, and the adiabatic energy gap of the [Fe(NCH)6]2+ ion. The molecular structures were optimized by DFT using the various functionals and basis sets listed in the first column. The time-steps chosen for the DMC simulation are also indicated. Differences in energy are well converged for Δτ = 0.0125 a.u.

Generic image for table
Table XIII.

DMC total energy for the LS state, the HS state, and the adiabatic energy gap of the [Fe(CO)6]2+ ion. The molecular structures were optimized by DFT using the functionals and the basis sets listed in the first column. The time-steps chosen for the DMC simulation are also indicated. Differences in energy are well converged for Δτ = 0.0125 a.u.

Generic image for table
Table XIV.

Adiabatic energy gap, ΔE adia, for the four ions calculated with the OLYP and HCTH407 functionals (the basis set C was used).

Generic image for table
Table XV.

The adiabatic energy gap for [Fe(H2O)6]2+ calculated by using various wave-function methods (reference to the literature is given in the second column). The values labelled as corr-CASSCF and corr-CASPT denote, respectively, the CASSCF and CASPT values after having applied an empirical correction of the order of 4000 cm−1 (see main text). Pierloot and Vancoilie67 provide an additional long list of results obtained by using different basis sets, geometries, and symmetries. Here, we report only the value that these authors indicate as the “best.”

Generic image for table
Table XVI.

Adiabatic energy gaps for [Fe(NH3)6]2+ calculated by using various wave-function methods (reference to the literature is given in the second column). The values labelled as corr-CASSCF and corr-CASPT denote, respectively, the CASSCF and CASPT values after having applied the empirical correction of the order of 4000 cm−1 (see main text).

Loading

Article metrics loading...

/content/aip/journal/jcp/137/12/10.1063/1.4752411
2012-09-24
2014-04-20
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Assessment of density functional theory for iron(II) molecules across the spin-crossover transition
http://aip.metastore.ingenta.com/content/aip/journal/jcp/137/12/10.1063/1.4752411
10.1063/1.4752411
SEARCH_EXPAND_ITEM