First principles study of the ground and excited states of FeO, FeO+, and FeO−

Sakellaris, Constantine N.; Miliordos, Evangelos; Mavridis, Aristides

doi:10.1063/1.3598529

Cited by 69 publications

(67 citation statements)

References 81 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For FeO-NiO, somewhat larger errors were observed for the quantum chemical approaches [60][61][62] (0.9-1.7%) while similar accuracy was maintained in DMC (0.3(1)%). The most challenging dimers overall were the weakly bound CuO and ZnO.…”

Section: B Dimer Propertiesmentioning

confidence: 89%

“…Over this same range, quantum chemistry 58,59 performs significantly better with MAD's of 4-16 cm −1 . For the mid-row FeO-NiO, DMC performs comparatively well with a MAD of 25(4) cm −1 (49(4) cm −1 for TM) for versus 53-84 cm −1 for quantum chemistry [60][61][62] . Finally, for CuO and ZnO the performance is similar between our DMC work and the available coupled cluster calculations, with absolute deviations of 60(1) cm −1 for CuO (68 cm −1 RCCSD(T) 63 ) and 18(8) cm −1 for ZnO (11 cm −1 RCCSD(T) 64 ).…”

Section: B Dimer Propertiesmentioning

confidence: 95%

“…Note that prior DMC data is not available for the heavier elements (FeO-ZnO). In addition to displaying DMC results from the present (DMC-TM/DMC-OPT) and prior (DMCprev) studies 20,24,57 , Figure 2 contains reference data from high-level quantum chemical calculations [58][59][60][61][62][63][64] , including multi-reference configuration interaction at the level of singles and doubles excitations (denoted MRCI or MRCI+Q with a Davidson-like correction), and restricted/unrestricted coupled cluster with singles, doubles, and perturbative triples (RCCSD(T)/UCCSD(T)). In the discussion below, the deviation from experiment of these three quantum chemical methods is expressed as a range rather than three separate and individually labeled numbers for brevity.…”

Section: B Dimer Propertiesmentioning

confidence: 99%

See 2 more Smart Citations

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

2016

View full text Add to dashboard Cite

Quantum Monte Carlo (QMC) calculations of transition metal oxides are partially limited by the availability of high quality pseudopotentials that are both accurate in QMC and compatible with major planewave electronic structure codes. We have generated a set of neon core pseudopotentials with small cutoff radii for the early transition metal elements Sc to Zn within the local density approximation of density functional theory. The pseudopotentials have been directly tested for accuracy within QMC by calculating the first through fourth ionization potentials of the isolated transition metal (M) atoms and the binding curve of each M-O dimer. We find the ionization potentials to be accurate to 0.16(1) eV, on average, relative to experiment. The equilibrium bond lengths of the dimers are within 0.5(1)% of experimental values, on average, and the binding energies are also typically accurate to 0.18(3) eV. The level of accuracy we find for atoms and dimers is comparable to what has recently been observed for bulk metals and oxides using the same pseudpotentials. Our QMC pseudopotential results also compare well with the findings of previous QMC studies and benchmark quantum chemical calculations.PACS numbers: 71.15.Dx, 71.15.Nc Transition metal oxides are an essential class of materials for energy applications. These materials find applications as diverse as catalysis, energy storage, and superconductivity. The ability to tailor the electronic functionality of transition metal oxides is clearly bolstered by continuing to develop a detailed theoretical understanding of these materials. Unfortunately it is this same class of materials that presents some of the greatest resistance to detailed theoretical characterization. Part of this challenge directly relates to the more localized electrons occupying the partially filled d states of the transition metal cations, leading to strong electron-electron interactions. Early characterizations of transition metal oxides by band theory incorrectly predicted many of them to be metals 1 . This departure from the expectations of band theory has lead to the widespread acceptance of strong electron correlation in these materials, in essence meaning that the Coulomb repulsion among electrons needs to be taken into account with some care. Continuum quantum Monte Carlo (QMC) methods 2 have the potential to address this need, as they are capable of taking the many body correlations of interacting electrons explicitly into account with few fundamental approximations. Though the application of such methods generally comes at a high computational cost, with the dramatic increase in available computing power seen in recent years these methods are now being brought to bear 3-9 on this challenging class of materials.One of the most prominent approximations involved in the practical application of quantum Monte Carlo techniques is the use of pseudopotentials to remove the high-energy core electrons. The fundamental idea behind pseudopotentials is that they preserve the electronic characteri...

show abstract

Section: B Dimer Propertiesmentioning

confidence: 89%

Section: B Dimer Propertiesmentioning

confidence: 95%

Section: B Dimer Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

2016

View full text Add to dashboard Cite

show abstract

“…This active space is similar to previous CASSCF/ MRCI studies on FeO + . 45,46 No spin−orbit coupling was considered. Experimental splittings between the sextet and quartet states are available for Fe + and FeO + , being 24.1 and 47.3 kJ/mol, respectively.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Further Insight into the Reaction FeO⁺+ H₂→ Fe⁺+ H₂O: Temperature Dependent Kinetics, Isotope Effects, and Statistical Modeling

et al. 2014

View full text Add to dashboard Cite

The reactions of FeO + with H 2 , D 2 , and HD were studied in detail from 170 to 670 K by employing a variable temperature selected ion flow tube apparatus. High level electronic structure calculations were performed and compared to previous theoretical treatments. Statistical modeling of the temperature and isotope dependent rate constants was found to reproduce all data, suggesting the reaction could be well explained by efficient crossing from the sextet to quartet surface, with a rigid near thermoneutral barrier accounting for both the inefficiency and strong negative temperature dependence of the reactions over the measured range of thermal energies. The modeling equally well reproduced earlier guided ion beam results up to translational temperatures of about 4000 K.

show abstract

“…Other 3d transition-metal/first-row-atom diatomic species have proven to have similar challenges. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] These studies illustrate the power of the MRCI approach, which has consistently been shown to be a reasonably robust way of investigating low-lying excited states of these systems to usually at least semi-quantitative accuracy when compared against experiment. However, the studies also demonstrate the limitations of even these very high accuracy methods, e.g.…”

Section: Introductionmentioning

confidence: 97%

Ab initiocalculations to support accurate modelling of the rovibronic spectroscopy calculations of vanadium monoxide (VO)

2016

View full text Add to dashboard Cite

Accurate knowledge of the rovibronic near-infrared and visible absorption spectra of transition metal diatomic species like vanadium monoxide (VO) is very important for studies of cool stellar and hot planetary atmospheres. Here, the required ab initio curves are produced for the dipole moment and spin-orbit coupling, both diagonal and off-diagonal. The reliability of these curves is estimated by comparing potential energy surfaces obtained using the same methodology against experimental data (e.g. excitation energies, vibrational frequencies, bond distances). The ab initio data produced here forms the basis of a new spectroscopic model for the rovibronic spectroscopy of VO. This model has been used to produce a new VO line list which considers 13 different electronic states and contains almost 640,000 energy levels and over 277 million transitions.Open shell transition metal diatomics are challenging species to model through ab initio quantum mechanics due to the large number of low-lying electronic states, significant relativistic effects (particularly strong spin-orbit coupling within and between electronic states) and strong static and dynamic electron correlation. Multi-reference configuration interaction (MRCI) methodologies using orbitals from a complete active space self-consistent-field (CASSCF) calculation are the standard technique for this kinds of system. We use different state-specific or minimal-state CASSCF orbitals for each electronic state to maximise the accuracy of the calculation. We demonstrate that this choice of orbitals significantly affects the quality of the property calculations by comparing results using CASSCF orbitals optimised for different numbers of states.The off-diagonal dipole moment, or the transition moment, is the critical property controlling the intensity of electronic transitions. We test the use of finite-field off-diagonal dipole moments, but found that (1) the accuracy of the excitation energies were not sufficient to allow accurate dipole moments to be evaluated and (2) computer time requirements for perpendicular transitions were prohibitive. The best off-diagonal dipole moments are calculated using wavefunctions with different CASSCF orbitals.

show abstract

First principles study of the ground and excited states of FeO, FeO+, and FeO−

Cited by 69 publications

References 81 publications

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Further Insight into the Reaction FeO⁺+ H₂→ Fe⁺+ H₂O: Temperature Dependent Kinetics, Isotope Effects, and Statistical Modeling

Ab initiocalculations to support accurate modelling of the rovibronic spectroscopy calculations of vanadium monoxide (VO)

Contact Info

Product

Resources

About

First principles study of the ground and excited states of FeO, FeO+, and FeO−

Cited by 69 publications

References 81 publications

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Pseudopotentials for quantum Monte Carlo studies of transition metal oxides

Further Insight into the Reaction FeO++ H2→ Fe++ H2O: Temperature Dependent Kinetics, Isotope Effects, and Statistical Modeling

Ab initiocalculations to support accurate modelling of the rovibronic spectroscopy calculations of vanadium monoxide (VO)

Contact Info

Product

Resources

About

Further Insight into the Reaction FeO⁺+ H₂→ Fe⁺+ H₂O: Temperature Dependent Kinetics, Isotope Effects, and Statistical Modeling