Twenty Years of Exceptional Success: The \u3cstrong\u3eM\u3c/strong\u3eolecular \u3cstrong\u3eE\u3c/strong\u3education and \u3cstrong\u3eR\u3c/strong\u3eesearch \u3cstrong\u3eC\u3c/strong\u3eonsortium in \u3cstrong\u3eU\u3c/strong\u3endergraduate computational chemist\u3cstrong\u3eRY\u3c/strong\u3e (\u3cstrong\u3eMERCURY\u3c/strong\u3e)”

The molecular education and research consortium in undergraduate computational chemistry (MERCURY) consortium, established in 2000, has contributed greatly to the scientific development of faculty and undergraduates. The MERCURY faculty peer-reviewed publication rate from 2001 to 2019 of 1.7 papers/faculty/year is 3.4 times the rate of the physical science faculty at primarily undergraduate institutions. We have worked with over 1000 students on research projects since 2001, and 75% of our undergraduate research students have been under-represented in chemistry, either female or students of color. Approximately half of our alumni attend graduate school for the purpose of obtaining advanced degrees in STEM fields, and two-thirds are female and/or students of color. We have had more than 1600 attendees at 18 MERCURY conferences, including 111 invited speakers, 61 of whom have been female and/or faculty of color. In this paper, the research accomplishments, transfor- mational outcomes, and scientific productivity of the MERCURY faculty are highlighted

The \u3cstrong\u3eM\u3c/strong\u3eolecular \u3cstrong\u3eE\u3c/strong\u3education and \u3cstrong\u3eR\u3c/strong\u3eesearch \u3cstrong\u3eC\u3c/strong\u3eonsortium in \u3cstrong\u3eU\u3c/strong\u3endergraduate computational chemist\u3cstrong\u3eRY\u3c/strong\u3e (MERCURY): Twenty Years of Exceptional Success Supporting Undergraduate Research and Inclusive Excellence

The author discusses the history of the Molecular Education and Research Consortium in Undergraduate Computational Chemistry (MERCURY), which has made significant contributions benefiting science faculty and undergraduates. The peer review publication rate of 1.7 for MERCURY faculty is 3.4 times the average rate for physical science faculty at primarily undergraduate institutions. Since 2001, 888 students have worked on research projects; 75 percent of them have come from underrepresented populations, such as female students or students of color. Approximately half of all graduates have pursued advanced degrees in STEM fields; two-thirds of this group have been female and/or students of color. More than 1,600 people have attended the 18 MERCURY conferences that have hosted 111 speakers, including 61 who were faculty members of color or female

Maintaining a High Degree of Research Productivity at a PUI as Your Career Advances

In this perspective, two experienced academic administrators who are computational chemists discuss strategies for how to maintain an active research program at a pre- dominately undergraduate institution as your career progresses. More responsibility equates to less time for research, so planning for research to remain a priority is essential. We all have the same amount of time, so figuring out how to use yours bet- ter is the key to remaining active. Professional organizations such as Council on Undergraduate Research, consortia of computational chemists such as Molecular Education and Research Consortium in computational chemistRY and Midwest Undergraduate Computational Chemistry Consortium, and attendance at profes- sional conferences can help sustain your research program. Collaborations with fac- ulty at other institutions provide a particularly effective accountability mechanism as well. Perhaps the best way to improve your productivity is to become a better men- tor to your undergraduate students. Building a research group that is fun and exciting develops a culture that sustains itself and provides the momentum necessary to maintain progress toward scientific goals

Computational Study of the Hydration of Sulfuric Acid Dimers: Implications for Acid Dissociation and Aerosol Formation

We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H2SO4)2(H2O)n where n = 0−6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature for a system consisting of two sulfuric acid molecules and up to six waters. At 0 K, a cluster of two sulfuric acid molecules and one water remains undissociated. Addition of a second water begins the deprotonation of the first sulfuric acid leading to the di-ionic species (the bisulfate anion HSO4−, the hydronium cation H3O+, an undissociated sulfuric acid molecule, and a water). Upon the addition of a third water molecule, the second sulfuric acid molecule begins to dissociate. For the (H2SO4)2(H2O)3 cluster, the di-ionic cluster is a few kcal mol−1 more stable than the neutral cluster, which is just slightly more stable than the tetra-ionic cluster (two bisulfate anions, two hydronium cations, and one water). With four water molecules, the tetra-ionic cluster, (HSO4−)2(H3O+)2(H2O)2, becomes as favorable as the di-ionic cluster H2SO4(HSO4−)(H3O+)(H2O)3 at 0 K. Increasing the temperature favors the undissociated clusters, and at room temperature we predict that the di-ionic species is slightly more favorable than the neutral cluster once three waters have been added to the cluster. The tetra-ionic species competes with the di-ionic species once five waters have been added to the cluster. The thermodynamics of stepwise hydration of sulfuric acid dimer is similar to that of the monomer; it is favorable up to n = 4−5 at 298 K. A much more thermodynamically favorable pathway forming sulfuric acid dimer hydrates is through the combination of sulfuric acid monomer hydrates, but the low concentration of sulfuric acid relative to water vapor at ambient conditions limits that process

Hydration of the Sulfuric Acid−Methylamine Complex and Implications for Aerosol Formation

The binary H2SO4−H2O nucleation is one of the most important pathways by which aerosols form in the atmosphere, and the presence of ternary species like amines increases aerosol formation rates. In this study, we focus on the hydration of a ternary system of sulfuric acid (H2SO4), methylamine (NH2CH3), and up to six waters to evaluate its implications for aerosol formation. By combining molecular dynamics (MD) sampling with high-level ab initio calculations, we determine the thermodynamics of forming H2SO4(NH2CH3)(H2O)n, where n = 0−6. Because it is a strong acid−base system, H2SO4−NH2CH3 quickly forms a tightly bound HSO4−−NH3CH3+ complex that condenses water more readily than H2SO4 alone. The electronic binding energy of H2SO4−NH2CH3 is −21.8 kcal mol−1 compared with −16.8 kcal mol−1 for H2SO4−NH3 and −12.8 kcal mol−1 for H2SO4−H2O. Adding one to two water molecules to the H2SO4−NH2CH3 complex is more favorable than adding to H2SO4 alone, yet there is no systematic difference for n ≥ 3. However, the average number of water molecules around H2SO4−NH2CH3 is consistently higher than that of H2SO4, and it is fairly independent of temperature and relative humidity

The Driving Effects of Common Atmospheric Molecules for Formation of Clusters: the Case of Sulfuric Acid, Formic Acid, Hydrochloric Acid, Ammonia, and Dimethylamine

One of the main sources of uncertainty for understanding global warming is understanding the formation of larger secondary aerosols. The beginning stages start with the formation of prenucleation complexes from precursor monomers of acids, bases, and organic molecules. The detailed interactions responsible for prenucleation and subsequent aerosol formation are difficult to decipher experimentally. We present a computational chemistry study of the interactions between three different acid molecules and two different bases. By combining a comprehensive search routine covering many thousands of configurations at the semiempirical level with high level quantum chemical calculations of approximately 1000 clusters for every possible combination of clusters containing a sulfuric acid molecule, a formic acid molecule, a hydrochloric acid molecule, an ammonia molecule, a dimethylamine molecule, and 0–3 water molecules, we have completed an exhaustive search of the DLPNO-CCSD(T)/CBS//ωB97X-D/6-31++G** Gibbs free energy surface for this system. This first detailed study of HCl interacting with two other acids and two bases reveals the subtleties that exist in the formation of prenucleation complexes for this system. We find that nitric acid forms stronger interactions in dry clusters than hydrochloric acid does. Often as the clusters grow larger with hydration, the sequential energies of clusters containing hydrochloric acid become more favorable than those with nitric acid. The detailed geometries of each minimum free energy cluster are often more important than traditional acid or base strength, which makes a priori prediction of which atmospheric species will be most important for driving prenucleation growth quite difficult. The results presented in this paper add to the conclusions that hydrogen bond topology and the detailed structural interactions that are subtle interplays between enthalpy and entropy are as important as conventional ideas such as acid/base strength

The Nature of the UV/X-Ray Absorber in PG 2302+029

We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029. This quasar has a rare system of ultra-high velocity (-56,000 km/s) UV absorption lines that form in an outflow from the active nucleus (Jannuzi et al. 2003). The Chandra data indicate that soft X-ray absorption is also present. We perform a joint UV and X-ray analysis, using photoionization calculations, to detemine the nature of the absorbing gas. The UV and X-ray datasets were not obtained simultaneously. Nonetheless, our analysis suggests that the X-ray absorption occurs at high velocities in the same general region as the UV absorber. There are not enough constraints to rule out multi-zone models. In fact, the distinct broad and narrow UV line profiles clearly indicate that multiple zones are present. Our preferred estimates of the ionization and total column density in the X-ray absorber (log U=1.6, N_H=10^22.4 cm^-2) over predict the O VI 1032, 1038 absorption unless the X-ray absorber is also outflowing at ~56,000 km/s, but they over predict the Ne VIII 770, 780 absorption at all velocities. If we assume that the X-ray absorbing gas is outflowing at the same velocity of the UV-absorbing wind and that the wind is radiatively accelerated, then the outflow must be launched at a radius of < 10^15 cm from the central continuum source. The smallness of this radius casts doubts on the assumption of radiative acceleration.Comment: Accepted for Publication in Ap

Water-Mediated Peptide Bond Formation in the Gas Phase: A Model Prebiotic Reaction

The emergence of life on the prebiotic Earth must have involved the formation of polypeptides, yet the polymerization of amino acids is thermodynamically unfavorable under biologically relevant aqueous conditions because amino acids are zwitterions in solution and because of the production of a water molecule through a condensation reaction. Many mechanisms for overcoming this thermodynamic unfavorability have been proposed, but the role of gas phase water clusters has not been investigated. We present the thermodynamics of the water-mediated gas phase dimerization reaction of glycine as a model for the atmospheric polymerization of amino acids prior to the emergence of biological machinery. We hypothesize that atmospheric aerosols may have played a major role in the prebiotic formation of peptide bonds by providing the thermodynamic driving force to facilitate increasingly stable linear oligopeptides. In addition, we hypothesize that small aerosols orient amino acids on their surfaces, thus providing the correct molecular orientations to funnel the reaction pathways of peptides through transition states that lead eventually to polypeptide products. Using density functional theory and a thorough configurational sampling technique, we show that the thermodynamic spontaneity of the linear dimerization of glycine in the gas phase can be driven by the addition of individual water molecules