Ryan P. Steele

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Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package,(More)
A summary of the technical advances that are incorporated in the fourth major release of the Q-CHEM quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation(More)
BACKGROUND Although the identification and management of anaphylaxis in an emergency department setting has been well studied, our understanding of the risk factors for admission in a community-based hospital is lacking. OBJECTIVE To determine the demographics and the predictors of hospitalization, in patients presenting with anaphylaxis to a(More)
TFE3 and TFEB are broadly expressed transcription factors related to the transcription factor Mitf. Although they have been linked to cytokine signaling pathways in nonlymphoid cells, their function in T cells is unknown. TFE3-deficient mice are phenotypically normal, whereas TFEB deficiency causes early embryonic death. We now show that combined(More)
Many chemical reactions in atmospheric aerosols and bulk aqueous environments are influenced by the surrounding solvation shell, but the precise molecular interactions underlying such effects have rarely been elucidated. We exploited recent advances in isomer-specific cluster vibrational spectroscopy to explore the fundamental relation between the hydrogen(More)
Analytic gradients of dual-basis Hartree-Fock and density functional theory energies have been derived and implemented, which provide the opportunity for capturing large basis-set gradient effects at reduced cost. Suggested pairings for gradient calculations are 6-31G/6-31G**, dual[-f,-d]/cc-pVTZ, and 6-311G*/6-311 + +G(3df,3pd). Equilibrium geometries are(More)
The resolution-of-the-identity (RI) approximation has placed the onus of the cost of a second-order Moller-Plesset (MP2) calculation on the underlying self-consistent field (SCF) calculation for many moderately sized molecules. A dual-basis approach to the SCF calculation, based on previous methods demonstrated for density functional theory, is combined(More)
For a system which undergoes electron or energy transfer in a polar solvent, we define the diabatic states to be the initial and final states of the system, before and after the nonequilibrium transfer process. We consider two models for the system-solvent interactions: A solvent which is linearly polarized in space and a solvent which responds linearly to(More)
Accurate potential energy surfaces for benzene.M complexes (M = Li+, Na+, K+, and NH4+) are obtained using coupled-cluster theory through perturbative triple excitations, CCSD(T). Our computations show that off-axis cation-pi interactions, where the cation is not directly above the aromatic ring, can be favorable and may influence molecular recognition.(More)
This article presents a general computational approach for efficient simulations of anharmonic vibrational spectra in chemical systems. An automated local-mode vibrational approach is presented, which borrows techniques from localized molecular orbitals in electronic structure theory. This approach generates spatially localized vibrational modes, in(More)