Publications

Displaying 1 - 25 of 50

Ab Initio Study of the Reactions Between a Series of Substituted Singlet Nitrenium Ions and Water

October 12, 2021

Author(s)

A A. Restrepo-Cossio, M Marquez, F Mari, Carlos A. Gonzalez

Highly correlated ab initio molecular orbital calculations have been used to study the energetics and mechanisms governing the reactions of a series of substituted singlet nitrenium ions ( 1[R-N-H] +, R=H, Cl, F, CN and Me) and water in gas phase and in

Comparative Ab initio Treatment (Hartree-Fock, Density-Functional Theory, MP2 and Quadratic Configuration Interactions) of the Cycloaddition of Phosphorus Ylides with Formaldehyde

October 12, 2021

Author(s)

A A. Restrepo-Cossio, Carlos A. Gonzalez, F Mari

In this study we describe the results of the application of several ab initio methods to the reactions of four unstabilized ylides (H[d3]P=CH[d2], H[d2]MeP=CH[d2], HMe[d2]P=CH[d2] and Me[d3]P=CH[d2]) with formaldehyde to form their respective

Electronic Structure Effects on the Formation and the Stability of Suspended Transition Metal Monatomic Chains

October 12, 2021

Author(s)

A Hasmy, Luis C. Rincon, R M. Hernandez, V Mujica, M Marquez, Carlos A. Gonzalez

In spite of the intense research activities devoted to the study of the achieved thinner wire (a suspended linear monatomic chain (1-19)), the high stability and the linear structure that this chain exhibits still remain a mysterious(11; 12). Moreover, the

Electronic Structure Rearrangements as a Source of Negative Differential Resistance in Molecules

October 12, 2021

Author(s)

Y Simon-Manso, Carlos A. Gonzalez, V Mujica, Y Aray, M Ratner

A qualitative explanation for the experimentally observed negative differential resistance (NDR) in current-voltage characteristics of molecule-metal tunneling junctions is provided. The model is based in DFT calculations of the electronic structure of

Systematic Study of Cancellation of Errors in the Benzene Dimer Interaction Energy

October 12, 2021

Author(s)

Ines Gonzalez, Stephen L. Garrison, M Marquez, Carlos A. Gonzalez, E C. Lim

We present a broadly applicable method or diagnostic for the appropriateness of the counterpoise correction and illustrate its value via calculations on the benzene dimer. The results also explain the fortuitous cancellation of errors that led to good

Theoretical Evidence for C-F Bond Activation by a Fluoro-calix[4]Pyrrole-tert-Amine Macrocycle

October 12, 2021

Author(s)

Fredrik Haeffner, M Marquez, Carlos A. Gonzalez

Density Functional Theory as well as highly correlated ab initio molecular orbital theory was used to explore the possibility of activating C-F bonds in fluoroalkanes by organic macrocyles. The results indicate that the reaction between fluoro-calix[4

Harnessing Measurement Science to Advance Food Safety

April 15, 2020

Author(s)

Melissa M. Phillips, David M. Bunk, Carlos A. Gonzalez, Scott A. Jackson, Leah R. Kauffman, Katrice A. Lippa, Catherine A. Rimmer, Stephen Semancik, Michael R. Winchester, Laura J. Wood

Opportunities for National Metrology Institutes and Reference Material Producers to Ensure Global Food Safety: A Companion Report

April 15, 2020

Author(s)

Melissa M. Phillips, David M. Bunk, Carlos A. Gonzalez, Scott A. Jackson, Leah R. Kauffman, Katrice A. Lippa, Catherine A. Rimmer, Stephen Semancik, Michael R. Winchester, Laura J. Wood

Visual Mass-Spec Share (vMS-Share): A New Public Web-Based Mass Spectrometry Visualization and Data Mining Repository

March 21, 2019

Author(s)

Niksa Blonder, Benjamin C. Orsburn, Josip Blonder, Carlos A. Gonzalez

Herein we introduce the Visual Mass-Spec Share (vMS-Share), a new public mass spectrometric (MS) repository and data mining website/resource freely accessible at https://vmsshare.nist.gov. vMS-Share is a webbased application developed for instant

Exploring the Borderland between Physics and Chemistry: Theoretical Methods in the Study of Atomic Clusters

December 10, 2010

Author(s)

Yamil Simon, Carlos A. Gonzalez, Patricio Fuentealba

Experimental and theoretical studies of atomic clusters have proven to be a challenging research theme, but also one of great practical importance in developing new technologies [1 and references therein]. The physical and chemical properties of atomic

Ionic Hydrogen bond Networks and Ion Solvation 1. An Efficient Monte Carlo / Quantum Mechanical Method for Structural Search and Energy Computation: Ammonium / Water

February 25, 2009

Author(s)

Yi-Lei Zhao, Michael Mautner, Carlos A. Gonzalez

Hydrogen bond networks about solvated ions can form many alternative structures, requiring extensive conformational searches with accurate but affordable energy computation. Combining Monte Carlo searches with the OPLS-AA force field plus geometry

Identification of Active Sites of Biomolecules II: Saccharide and Transition Metal ion in Aqueous Solution

February 23, 2009

Author(s)

Orkid Coskuner, Denis E. Bergeron, Luis C. Rincon, Jeffrey W. Hudgens, Carlos A. Gonzalez

We discuss the coordination mechanism of FeIII and methyl-a-mannopyranoside in aqueous solution using a recently presented integrated approach comprising ab initio electronic structure calculations, molecular dynamics simulations, and mass spectrometric

Phosphine Polymerization by Nitric Oxide: Experimental Characterization and Theoretical Predictions of Mechanism

December 22, 2008

Author(s)

Yi-Lei Zhao, Jason W. Flora, Stephen Garrison, Carlos A. Gonzalez, K. N. Houk, Manuel Marquez

A yellow solid material [PxHy] has been obtained in the reaction of phosphine (PH3) and nitric oxide (NO) at room temperature, and characterized by TGA-MS and ATR-FTIR, along with the previous SEM and X-ray fluorescence spectroscopy. In this work using

Crystal Asymmetry Induces Single-Atom Chain Formation in Gold Nanowires

October 16, 2008

Author(s)

Francesca Tavazza, A Hasmy, Lyle E. Levine, Anne M. Chaka, Luis C. Rincon, M Marquez, Carlos A. Gonzalez

We performed density functional theory and tight-binding molecular dynamics calculations to investigate the formation of suspended linear atom chains when stretching gold nanowires along the [110] crystal orientation. We determined that the chain formation

Ligand Exchange Reactions in the Formation of Diphosphine-Protected Gold Clusters

August 14, 2008

Author(s)

Denis E. Bergeron, Orkid Coskuner, Jeffrey W. Hudgens, Carlos A. Gonzalez

Electrospray ionization mass spectrometry is employed to study the formation of L3- and L5-protected gold clusters (L3 = 1,3-Bis(diphenylphosphino)propane; L5 = 1,5-Bis(diphenylphosphino)pentane), and it is found that molecular complexes in which Au+ is

Glycosidic Linkage Conformation of Methyl-alpha-Mannopyranoside

July 31, 2008

Author(s)

Orkid Coskuner, Denis E. Bergeron, Luis C. Rincon, Jeffrey W. Hudgens, Carlos A. Gonzalez

We study the preferred conformation of the glycosidic linkage of methyl--mannopyranoside in the gas phase and in aqueous solution. Results obtained utilizing Car Parrinello molecular dynamics (CPMD) simulations are compared to those obtained from

Extended Huckel Tight-Binding Approach to Electronic Excitations

July 25, 2008

Author(s)

Luis C. Rincon, Anwar Hasmy-Aguilar, Carlos A. Gonzalez, Rafael Almeida

In this work we propose the application of a self-consistent Extended Huckel Tight Binding method in the computation of the absorption optical spectrum of molecules within the linear response time dependent Density Functional formalism. The Extended Huckel

Impact of Swapping Ethyl for Phenyl Groups on Diphosphine-Protected Undecagold

September 1, 2007

Author(s)

Justin Golightly, Lin Gao, A W. Castleman, Denis E. Bergeron, Jeffrey W. Hudgens, Rudolph Magyar, Carlos A. Gonzalez

1,3-Bis(diethylphosphino)propane (depp) protected gold clusters are synthesized and studied via electrospray ionization mass spectrometry. An undecagold cluster, [Au11(depp)4Cl2]+, is observed under soft ionization conditions, and is found to persist in

N-Nitrosation of Amines by NO 2 and NO: A Theoretical Study

March 22, 2007

Author(s)

Yi-Lei Zhao, Stephen L. Garrison, Carlos A. Gonzalez, William D. Thweatt, M Marquez

Gas-phase nitrosation implies an alternative non-ionic pathway different from the nitrosonium-nitrosation by acidification of nitrite. Electronic structure calculations discussed in this work suggest a free radical mechanism, in which NO2 abstracts a

Chemisorption-Induced Spin Symmetry Breaking In Gold Clusters and the Onset of Paramagnetism in Capped Gold Nanoparticles

January 1, 2006

Author(s)

Carlos A. Gonzalez, Y Simon-Manso, M Marquez, V Mujica

We present a simple model to describe the induction of magnetic behavior on gold clusters upon chemisorption of one organic molecule with different chemical linkers. In particular, we address the problem of stability of the lowest-lying singlet and show

Approximate Self-Consistent Potentials for Density-Functional-Theory Exchange-Correlation Functionals

April 1, 2005

Author(s)

Mauricio Cafiero, Carlos A. Gonzalez

We show that potentials for exchange-correlation functionals within the Kohn-Sham Density Functional Theory framework may be written as potentials for simpler functionals multiplied by a factor close to unity, and in a self-consistent field calculation

Rapid Fixation of Methylene Chloride By a Macrocyclic Amine

March 1, 2005

Author(s)

J C. Lee, Keith J. Stanger, Bruce C. Noll, Carlos A. Gonzalez, M Marquez, Bradley D. Smith

A simple macrocyclic amine is alkylated by methylene chloride to give a quaternary ammonium chloride salt. When methylene chloride is the solvent, the reaction exhibits pseudo first order kinetics, and the reaction half-life at 25.0 C is 2.0 minutes. The

A Quasimolecular Approach to the Conductance of Molecule-Metal Junctions: Theory and Application to Voltage-Induced Conductance Switching

December 1, 2004

Author(s)

Carlos A. Gonzalez, Y Simon-Manso, J Batteas, M Marquez, M Ratner, V Mujica

Direct Combined ab Initio/Transition State Theory Study of the Kinetics of the Abstraction Reactions of Halogenated Methanes With Hydrogen Atoms

November 1, 2004

Author(s)

F Louis, Carlos A. Gonzalez, J P. Sawerysyn

Electrostatics for Exploring the Nature of the Hydrogen Bonding in Poly-ethylene Oxide Hydration

February 1, 2004

Author(s)

Y Aray, M Marquez, J Rodriguez, D Vega, Y Simon-Manso, S Coll, Carlos A. Gonzalez, D A. Weitz

Poly-ethylene oxide (PEO) is a nonionic surfactant of great scientific and technological interest for a wide variety of applications, many of which depend upon the properties of the polymer in aqueous solution. [1] It is commonly used as lubricants

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