Dissociation curves and binding energies of diatomic transition metal carbides from density functional theory

Abstract

ABSTRACT:The computational description of the catalytic processes on the surface of transition metals (TMs) requires methods capable of accurate prediction of the bond forming and breaking between the atoms of metal and other elements. In our previous report [Goel and Masunov, J Chem Phys, 129, 214302, 2008], we studied TM hydrides and found that Boese-Martin functional for kinetics (BMK) combined with broken symmetry approach described dissociation process more accurately than multireference wavefunction theory (WFT) methods and some other functionals. Here, we investigate the binding energy, geometry, electronic structure, and potential energy curves for diatomic TM carbides using several exchange-correlation functionals. The functionals that include explicit dependence on the kinetic energy density (s-functionals) are considered, among others. We have found M05-2x performance to be the best, followed by BMK, when compared with experimental and high level WFT energetics. This agreement deteriorates quickly for other functionals when the fraction of the Hartree-Fock exchange is decreased. Scalar relativistic corrections yield mixed results for bond lengths and bond energies. The natural bond orbital analysis provides useful insight in description of stable spin state over others in these diatomics.

Oxidative Addition of Dihydrogen to Divanadium in Solid Ne: Multiple‐Bonded Triplet HVVH and Singlet V2(μ‐H)2

“…Hence, the formation of the linear HVVH isomer is still exotherm by 0.62 eV. The 5 Δ ground state for VH is in line with previous calculations . The calculated fragmentation energy of HVVH by HVVH( 3 Σ g − )→2 VH( 5 Δ) amounts to 2.77 eV.…”

Diffusion Monte Carlo for Accurate Dissociation Energies of 3d Transition Metal Containing Molecules

“…Ref. [4][5][6][7]. Although some DFT functionals give astonishingly accurate results on average 7 , the strong correlation leads to a large dependence on the exchange-correlation (XC) functional (see for example Tab.…”

“…Consequently, various studies on transition metal containing dimers (TMCDs) have been published. The methods used include high-level quantum chemical methods, such as CASPT2, CI, and CCSD­(T) (e.g., refs − ), and also DFT or DFT + U (e.g., refs − ). Although some DFT functionals give astonishingly accurate results on average, the strong correlation leads to a large dependence on the exchange-correlation (XC) functional (see, for example, Table ).…”

“…More recently, quantum Monte Carlo (QMC) methods have also been applied to transition metal atoms, 11,12 TMCDs, 10,13−17 clusters, 18 and to solids, 19,20 including transition metals. The interest in applying QMC methods, such as reptation Monte Carlo and diffusion Monte Carlo (DMC), to these systems is sparked by the fact that QMC methods are able to treat correlation effects explicitly rather than using approximate density functionals while scaling as 4 , where c is a small constant and N is the number of particles, if a constant statistical error bar in the total energy is sought and localized basis functions are used. 21,22 This scaling with system size allows the treatment of large molecular complexes and solids such as transition metal oxides.…”

Multiconfiguration Pair-Density Functional Theory and Complete Active Space Second Order Perturbation Theory. Bond Dissociation Energies of FeC, NiC, FeS, NiS, FeSe, and NiSe

“…The ground states of FeC ( 3 Δ 3 ) and NiC ( 1 Σ + ) have been experimentally ,,, determined with the configurations of 1σ 2 2σ 2 1π 4 1δ 3 3σ 1 and 1σ 2 2σ 2 1π 4 1δ 4 3σ 2 , respectively. Several theoretical ,,− studies reported the bond dissociation energies of FeC and NiC using various wave function and density functional methods. The SP calculations for FeC give unusually small errors when compared to the corresponding CASSCF for each of the three CPO active schemes.…”