CCSD(T), W1, and other model chemistry predictions for gas-phase deprotonation reactions

A series of CCSD(T) single-point calculations on MP4(SDQ) geometries and the W1 model chemistry method have been used to calculate ΔH° and ΔG° values for the deprotonation of 17 gas-phase reactions where the experimental values have reported accuracies within 1 kcal/mol. These values have been compared with previous calculations using the G3 and CBS model chemistries and two DFT methods. The most accurate CCSD(T) method uses the aug-cc-pVQZ basis set. Extrapolation of the aug-cc-pVTZ and aug-cc-pVQZ results yields the most accurate agreement with experiment, with a standard deviation of 0.58 kcal/mol for ΔG° and 0.70 kcal/mol for ΔH°. Standard deviations from experiment for ΔG° and ΔH° for the W1 method are 0.95 and 0.83 kcal/mol, respectively. The G3 and CBS-APNO results are competitive with W1 and are much less expensive. Any of the model chemistry methods or the CCSD(T)/aug-cc-pVQZ method can serve as a valuable check on the accuracy of experimental data reported in the National Institutes of Standards and Technology (NIST) database.

Comparison of Model Chemistry and Density Functional Theory Thermochemical Predictions with Experiment for Formation of Ionic Clusters of the Ammonium Cation Complexed with Water and Ammonia; Atmospheric Implications

The G2, G3, CBS-QB3, and CBS-APNO model chemistry methods and the B3LYP, B3P86, mPW1PW, and PBE1PBE density functional theory (DFT) methods have been used to calculate ΔH° and ΔG° values for ionic clusters of the ammonium ion complexed with water and ammonia. Results for the clusters NH4+(NH3)n and NH4+(H2O)n, where n = 1−4, are reported in this paper and compared against experimental values. Agreement with the experimental values for ΔH° and ΔG° for formation of NH4+(NH3)n clusters is excellent. Comparison between experiment and theory for formation of the NH4+(H2O)n clusters is quite good considering the uncertainty in the experimental values. The four DFT methods yield excellent agreement with experiment and the model chemistry methods when the aug-cc-pVTZ basis set is used for energetic calculations and the 6-31G* basis set is used for geometries and frequencies. On the basis of these results, we predict that all ions in the lower troposphere will be saturated with at least one complete first hydration shell of water molecules.

I want to be my own person: the meaning-making and psychosocial processes of legacy students at Bucknell University

This study examined the meaning-making and psychosocial processes of five female legacy students at Bucknell University, each of whom having had at least one parent graduate from the institution. With a research philosophy, design, and methodology rooted in qualitative inquiry and phenomenology, inductive data analysis led to three primary categories that underscored legacy identity development. The first, Paradox of Influence and Identity, revealed through six themes nuanced experiences of separation-individuation. Second, Teaching and Learning, comprised of five themes, illuminated the impact of family — and of Bucknell parent alumni in particular — on their children’s internal working models. Lastly, Bucknell — the Environmental Contextand the five themes grouped therein highlighted the contributions of University community members, and of the campus culture and climate itself, to the co-construction of psychosocial formation. A tentative outline of grounded theory was offered, which explored categorical relationships; Paradox of Influence and Identity emerged as thedominant phenomenon, informing and being reinforced by the data of Teaching and Learning and Bucknell — the Environmental Context. Provisional intervention strategies for student affairs practice, in the contexts of academics, residential life, and career development, were discussed. Further, triangulated research is needed to substantiate and evolve the findings and theoretical model of this thesis.