Environmental Molecular Sciences Laboratory

About: Environmental Molecular Sciences Laboratory is a facility organization based out in Richland, Washington, United States. It is known for research contribution in the topics: Mass spectrometry & Ion. The organization has 1471 authors who have published 3010 publications receiving 169961 citations.

An implementation of RI–SCF on parallel computers

Abstract: The resolution of the identity (RI) approximation to the Hartree–Fock method was implemented within the NWChem suite of ab initio programs for parallel computers. After a description of the method, a detailed account of the implementation is given. We present a sample calculation and compare its performance and accuracy to an “exact” direct SCF calculation. Problems and limitations of the method are also discussed. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 63–69, 1997

Photoelectron spectroscopy of doubly and singly charged group VIB dimetalate anions: M2O72-, MM'O72-, and M2O7- (M, M' = Cr, Mo, W).

Abstract: We produced both doubly and singly charged Group VIB dimetalate species-M2O7 2-, MM'O72-, and M2O7 - (M, M'=) Cr, Mo, W)susing two different experimental techniques (electrospray ionization for the doubly charged anions and laser vaporization for the singly charged anions) and investigated their electronic and geometric structures using photoelectron spectroscopy and density functional calculations. Distinct changes in the electronic and geometric structures were observed as a function of the metal and charge state. The electron binding energies of the heteronuclear dianions MM'O7 2- were observed to be roughly the average of those of their homonuclear counterparts (M2O7 2- and M'2O7 2-). Density functional calculations indicated that W2O7 2-, W2O7-, and W2O7 possess different ground-state structures: the dianion is highly symmetric (D3d,1A1g) with a single bridging oxo ligand, the monoanion is a doublet (C1, 2A) with two bridging oxo ligands and a radical terminal oxo ligand, whereas the neutral is a singlet (C1, 1A) with two bridging oxo ligands and a terminal peroxo ligand. The combined experimental and theoretical study provides insights into the evolution of geometric and electronic structures as a function of charge state. The clusters identified might provide insights into the possible structures of reactive species present inmore » early transition-metal oxide catalysts that are relevant to their reactivity and catalytic function.« less

Method for unknown vapor characterization and classification using a multivariate sorption detector. Initial derivation and modeling based on polymer-coated acoustic wave sensor arrays and linear solvation energy relationships

Abstract: A novel method for the characterization and classification of unknown vapors based on the response on an array of polymer-coated acoustic wave vapor sensors is presented. Unlike existing classification algorithms, the method does not require that the system be trained on all samples to be identified. Instead, the solvation parameters of the unknown vapor are estimated given the sensor responses and the linear solvation energy relationship coefficients of the sorbent polymer coatings. The vapors can then be identified from a database of candidate vapor parameters. The method is implemented in a way that is analogous to multivariate calibration with classical least squares, where the individual vapor parameters are treated as pure compounds. It is not necessary to know the vapor concentration of the vapor to perform the classification. In principle, it is possible to estimate the concentration of an unknown vapor for which the system has not been trained or calibrated. It is also possible to implement the m...

Airborne soil organic particles generated by precipitation

Abstract: Airborne organic particles affect Earth’s climate. Imaging of particles after rain events and experimental irrigation shows that water drop impaction of soils generates solid organic particles, with impacts on clouds and radiation absorption.