Density functional and multiconfigurational ab initio study of the ground and excited states of Os₂

Abstract

Multiconfigurational ab initio methods predict that the 5Πu state as the ground state instead of the 7Δu state. Although multiconfigurational perturbation theory correctly predicts the ground state, they overestimate the bond dissociation energy (BDE). Only multireference configuration interaction method can reasonably calculate the BDE. The spin‐orbit effect on the spectroscopic constants is not significant. The results calculated by density functional theory (DFT) vary significantly depending on the selection of a DFT functional. No DFT functional gives the same energy ordering as calculated by the second‐order multiconfigurational perturbation theory (CASPT2). The old generalized gradient approximations functionals are well suited for predicting the ground state and calculating the bond length and the vibrational frequency of Os2. According to the CASPT2 calculation, the ground state of Os2 has a quadruple bond. © 2014 Wiley Periodicals, Inc.

Structure Evolution of Transition Metal-doped Gold Clusters M@Au12 (M = 3d–5d): Across the Periodic Table

“…For Hf 2 , the revTPSS/SDD scheme gives 6 μ B for the GS, which is different from the experimental value and revTPSS/TZP value of 2 μ B . Previous studies reported the disagreement in the magnetic moment of Os 2 with values of 4 μ B or 6 μ B for the lowest energy structures. , We also found that the revTPSS/SDD and revTPSS/TZP methods give different magnetic moments for Os 2 dimer with values of 6 μ B and 4 μ B , respectively.…”

“…The rows starting with δ and δ̅ represent the average and overall average error between theoretical and experimental data, respectively. The van der Waals species (Zn 2 , Cd 2 , Hg 2 ) are not discussed in this work because there are all covalent or ionic interactions in M@Au 12 clusters. b Reference . c Reference . d Reference . e Reference . f Reference . g Reference . h Reference . i Reference . j Reference . k Reference . l Reference . m Reference . n Reference . o Reference . p Reference . …”

Multiconfiguration Pair-Density Functional Theory: A Fully Translated Gradient Approximation and Its Performance for Transition Metal Dimers and the Spectroscopy of Re2Cl82–

“…eV, respectively. 55 Considering the difficulty of the problem (the wide range of previous results) and the uncertainty in the experimental results, the tPBE and ftPBE results are both considered satisfactory.…”

“…PBE overestimates the Compared to other transition metal dimers, there are fewer theoretical studies on Os 2 . Due to its multiconfigurational character, the predictions depend strongly on the choice of functional and basis set, with the calculated ground state being either 7 Δ u or a 5 Π u [52][53][54][55]. In addition to a KS-DFT study, Kim et al55 reported CASSCF, CASPT2, MRMP2, and MRCI wave function results…”

Untitled

“…So, theoretical studies shed light onto studying different characteristics of the system with expense of computation time [6]. Nowadays, improvements in computer technology and DFT made theoretical In nanoscale, surface morphology of materials shows different characteristics compared to bulk size [9].The particle size of biomaterials used in the field of dentistry is decreased to below 100nm [10].…”