title: Pseudopotential-Based Correlation Consistent Composite Approach (rp-ccCA) for First- and Second-Row Transition Metal Thermochemistry.
abstract: The relativistic-pseudopotential correlation consistent composite approach (rp-ccCA) was used to determine the enthalpy of formation (ΔHf) of 24 first row (3d) transition metal compounds. The rp-ccCA-derived ΔHf's were compared to ΔHf's previously obtained with an all-electron composite method for transition metals (ccCA-TM). For the 3d metal systems, rp-ccCA achieves transition metal accuracy, within 3 kcal/mol of reliable experimental data, overall. By utilizing pseudopotentials within the rp-ccCA methodology, we observed a significant computational time savings (53%) in comparison to the all-electron basis sets employed within ccCA-TM. With the proven reliability and accuracy of rp-ccCA, the methodology was employed to construct a calibration set of 210 second-row (4d) transition metal compounds and their ΔHf's. The 4d calibration set is referred to as 4dHf-210. Within the 4dHf-210 set, there were 61 molecules with available experimental data. The average experimental uncertainty was 4.05 kcal/mol and the mean absolute deviation of rp-ccCA was 3.64 kcal/mol, excluding outliers (10 total). This study provides a large set of energetics that can be used to gauge existing and future computational methodologies and to aid experimentalists in reaction design.
authors.affiliation: Department of Chemistry and Center for Advanced Scientific Computing and Modeling, University of North Texas, Denton, Texas 76203-5017, United States.
authors.forename: Sivabalan
authors.initials: S
authors.lastname: Manivasagam
authors.affiliation: Department of Chemistry and Center for Advanced Scientific Computing and Modeling, University of North Texas, Denton, Texas 76203-5017, United States.
authors.forename: Marie L
authors.initials: ML
authors.lastname: Laury
authors.affiliation: Department of Chemistry and Center for Advanced Scientific Computing and Modeling, University of North Texas, Denton, Texas 76203-5017, United States.
authors.forename: Angela K
authors.initials: AK
authors.lastname: Wilson
mesh_terms: D002138:Calibration; D003198:Computer Simulation; D004583:Electrons; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D013816:Thermodynamics; D035501:Uncertainty
chemical_list: D008670:Metals