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A next‐generation protocol (Poltype 2) has been developed which automatically generates AMOEBA polarizable force field parameters for small molecules. Both features and computational efficiency have been drastically improved. Notable advances include improved database transferability using SMILES, robust torsion fitting, non‐aromatic ring torsion parameterization, coupled torsion‐torsion parameterization, Van der Waals parameter refinement using ab initio dimer data and an intelligent fragmentation scheme that produces parameters with dramatically reduced ab initio computational cost. Additional improvements include better local frame assignment for atomic multipoles, automated formal charge assignment, Zwitterion detection, smart memory resource defaults, parallelized fragment job submission, incorporation of Psi4 quantum package, ab initio error handling, ionization state enumeration, hydration free energy prediction and binding free energy prediction. For validation, we have applied Poltype 2 to ~1000 FDA approved drug molecules from DrugBank. The ab initio molecular dipole moments and electrostatic potential values were compared with Poltype 2 derived AMOEBA counterparts. Parameters were further substantiated by calculating hydration free energy (HFE) on 40 small organic molecules and were compared with experimental data, resulting in an RMSE error of 0.59 kcal/mol. The torsion database has expanded to include 3543 fragments derived from FDA approved drugs. Poltype 2 provides a convenient utility for applications including binding free energy prediction for computational drug discovery. Further improvement will focus on automated parameter refinement by experimental liquid properties, expansion of the Van der Waals parameter database and automated parametrization of modified bio‐fragments such as amino and nucleic acids.

The supercritical carbon dioxide medium, used to increase efficiency in oxy combustion fossil energy technology, may drastically alter both rates and mechanisms of chemical reactions. Here we investigate potential energy surface of the second most important combustion reaction with quantum chemistry methods. Two types of effects are reported: formation of the covalent intermediates and formation of van der Waals complexes by spectator CO2 molecule. While spectator molecule alter the activation barrier only slightly, the covalent bonding opens a new reaction pathway. The mechanism includes sequential covalent binding of CO2 to OH radical and CO molecule, hydrogen transfer from oxygen to carbon atoms, and CH bond dissociation. This reduces the activation barrier by 11 kcal/mol at the rate-determining step and is expected to accelerate the reaction rate. The finding of predicted catalytic effect is expected to play an important role not only in combustion but also in a broad array of chemical processes taking place in supercritical CO2 medium. It may open a new venue for controlling reaction rates for chemical manufacturing.

The supercritical carbon dioxide diluent is used to control the temperature and to increase the efficiency in oxycombustion fossil fuel energy technology. It may affect the rates of combustion by altering mechanisms of chemical reactions, compared to the ones at low CO concentrations. Here, we investigate potential energy surfaces of the four elementary reactions in the CH + O reactive system in the presence of one CO molecule. In the case of reaction CH + O → CHO + OH (R1 channel), van der Waals (vdW) complex formation stabilizes the transition state and reduces the activation barrier by ∼2.2 kcal/mol. Alternatively, covalently bonded CO may form a six-membered ring transition state and reduce the activation barrier by ∼0.6 kcal/mol. In case of reaction CH + O → CHO + O (R2 channel), covalent participation of CO lowers the barrier for the rate limiting step by 3.9 kcal/mol. This is expected to accelerate the R2 process, important for the branching step of the radical chain reaction mechanism. For the reaction CH + O → CHO + HO (R3 channel) with covalent participation of CO, the activation barrier is lowered by 0.5 kcal/mol. The reaction CHO + OH → CHO + HO (R4 channel) involves hydrogen abstraction from formaldehyde by OH radical. Its barrier is reduced from 7.1 to 0.8 kcal/mol by formation of vdW complex with spectator CO. These new findings are expected to improve the kinetic reaction mechanism describing combustion processes in supercritical CO medium.

Uranium trioxide in contact with water at about 180" gives an orthorhombic hydrate, U0,,0.8H2O, with the cell dimensions a = 10-23 & 0-01, b = 6.89 f 0.01, c = 4-28 & 0.01 A. These dimensions appear to vary slightly with deviation of the water content from 0-8 mole per uranium atom. Between 200" and 280' another phase appears, UO,,l*OH,O, also orthorhombic with cell dimensions a = 5.638 f 0.005, b = 6.273 f 0.005, c = 9-925 f 0.005 A, space-group Pbca. The hemihydrate, U0,,0.5Hz0,is stable in water above 250". A further phase, possibly due to a relatively high pH and probably triclinic, was observed when the uranium trioxide was heated in water at 230" in contact with glass.Some of the properties of these hydrates are described, together with observations on the preparation of pure anhydrous uranium trioxide from uranyl nitrate.PREVIOUS investigations on the hydrated oxides of uranium indicated that the trioxide is stable in water, up to high temperatures, and that over the range 70-300" (approx.) it forms a monohydrate.1 The system is quite complex, however, and Katz and Rabinowitz quoted the following four crystalline modifications observed by D. T. Vier : (i) a-UO,,H,O, large six-sided orthorhombic basal tablets ; (ii) B-UO,,H,O, small orthorhombic prismatic tablets with slightly larger unit cell than the a-form ; (iii) y-UO,,H,O, six-sided columnar crystals, with X-ray diffraction pattern similar to that of the a-and the @-form, but perhaps belonging to a different system : contains (0.9 mole of H20 per uranium atom; (iv) 8-UO3,H2O, triclinic, giving a complex X-ray diffraction pattern. The last form may be due to impurities.Very few details were given of the preparation and the relations between these various forms, and the present investigation was undertaken to obtain more extensive information in the range 180-320". The particular form of UO,,H,O obtained may be sensitive to the presence of traces of impurities, such as the soluble uranyl ion, and so some observations are made also on the preparation of uranium trioxide free from all contaminants down to a level of a few parts per million. EXPERIMENTALA sample (about 100 mg.) was suspended in a platinum boat on the end of a 35-cm. extension fibre from the lower end of the helix. The temperature of the sample was raised linearly at about 2"/min.