Chemistry Commons^™

Semiclassical Nonadiabatic Dynamics Using A Mixed Wave-Function Representation, Sophya Garashchuk, Vitaly A. Rassolov, George C. Schatz

Faculty Publications

Nonadiabatic effects in quantum dynamics are described using a mixed polar/coordinate space representation of the wave function. The polar part evolves on dynamically determined potential surfaces that have diabatic and adiabatic potentials as limiting cases of weak localized and strong extended diabatic couplings. The coordinate space part, generalized to a matrix form, describes transitions between the surfaces. Choice of the effective potentials for the polar part and partitioning of the wave function enables one to represent the total wave function in terms of smooth components that can be accurately propagated semiclassically using the approximate quantum potential and small basis sets. …

Semiconductor Nanowire Laser And Nanowire Waveguide Electro-Optic Modulators, Andrew B. Greytak, Carl J. Barrelet, Yat Li, Charles M. Lieber

Faculty Publications

Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaN nanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowire waveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.

Catena-Poly[[Bis(Α-Thenoyltrifluoroacetonato)Copper(Ii)]-Μ-1,4-Di-4-Pyridyl-2,3-Diazabuta-1,3-Diene], William J. Perkins, Tamara Maxwell, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

In the one-dimensional title polymer, [Cu(C₈H₄F₃O₂S)₂(C₁₂H₁₀N₄)]_n or [Cu(L)₂(tta)₂] [tta is -thenoyltrifluoroacetonato and L is 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene], Cu²⁺ lies on a center of inversion. It is axially coordinated by two pyridyl N atoms from two different L ligands and equatorially coordinated by four O atoms from two chelating tta ligands. The ligand L propagates the one-dimensional chain structure by serving as a bridging ligand between two Cu octahedra via Cu-N coordinate bonds.

Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith A. Tershany, Andrea M. Goforth, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C₁₂H₈N₂)₃](I₃)₂, contains one [Co(1,10-phenanthroline)₃]²⁺ cation, half each of two centrosymmetric triiodide anions, and one complete triiodide anion. The title compound was synthesized solvothermally from Co(NO₃)₂, 1,10-phenanthroline, and SnI₂, where the SnI₂ reagent serves only as a source of I atoms.

Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea M. Goforth, Rachael E. Hipp, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C₂H₈N₂)₃][Bi₂I₉], crystallizes in the orthorhombic space group Cmc2₁. The asymmetric unit contains half of a [Co(en)₃]³⁺ cation (en is ethylenediamine) and half of a [Bi₂I₉]^3- anion. Both species are located on mirror planes, requiring the [Co(en)₃]³⁺ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol-water solvent mixture using rac-[Co(en)₃]I₃ and bismuth triiodide …

Semiclassical Nonadiabatic Dynamics With Quantum Trajectories, Vitaly A. Rassolov, Sophya V. Garashchuk

Faculty Publications

Dynamics based on quantum trajectories with approximate quantum potential is generalized to nonadiabatic systems and its semiclassical properties are discussed. The formulation uses the mixed polar-coordinate space representation of a wave function. The polar part describes the overall time evolution of the wave-function components semiclassically using the single-surface approximate quantum potential. The coordinate part represents a complex“population” amplitude, which in case of localized coupling can be solved for quantum mechanically in an efficient manner. In the high-energy regime this is accomplished by using a small basis determined by the coupling between surfaces. An illustration is given for a typical curve-crossing …

Punishment And Rehabilitation Views Of Social Work Majors And Non-Social Work Students: An Exploratory Study, Eric G. Lambert, Sudershan Pasupuleti, Reva I. Allen

Journal of the South Carolina Academy of Science

No abstract provided.

Design And Cloning Of A Hammerhead Ribozyme Targeted Tohiv-1p7fmrna, Katherine L. Anderson, William H. Jackson

Journal of the South Carolina Academy of Science

No abstract provided.

Sm2Nairo6, A Monoclinically Distorted Double Perovskite, Samuel J. Mugavero Iii, Irina V. Puzdrjakova, Mark D. Smith, Hans-Conrad Zur Loye

Faculty Publications

Single crystals of the lanthanide-containing iridate, disamarium sodium iridium hexaoxide, Sm₂NaIrO₆, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/n and is a double perovskite, consisting of a 1:1 ordered rock-salt-type lattice of corner-shared NaO₆ and IrO₆ distorted octahedra. Samarium occupies the eightfold coordination site generated by the connectivity of the octahedra.

Modified Quantum Trajectory Dynamics Using A Mixed Wave Function Representation, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

Dynamics of quantum trajectories provides an efficient framework for description of various quantum effects in large systems, but it is unstable near the wave function density nodes where the quantum potential becomes singular. A mixed coordinate space/polar representation of the wave function is used to circumvent this problem. The resulting modified trajectory dynamics associated with the polar representation is nonsingular and smooth. The interference structure and the nodes of the wave function density are described, in principle, exactly in the coordinate representation. The approximate version of this approach is consistent with the semiclassical linearized quantum force method [S. Garashchuk and …

Resonance-Enhanced Multiphoton Ionization For Real-Time Monitoring Of Trichloroethylene Formed By Degradation Of Tetrachloroethylene Using Zero-Valent Zinc, Kui Chen, Jack E. Pender, John L. Ferry, S. Michael Angel

Faculty Publications

Resonance-enhanced multiphoton ionization (REMPI) is investigated as a potential technique for real-time monitoring of selected volatile organochloride compounds (VOCs). In a proof-of-concept experiment, the progress of the reductive-degradation of tetrachloroethylene (PCE) to trichloroethylene (TCE) by zero-valent zinc was monitored by REMPI measurements performed in the headspace above the PCE solution. Two-photon resonant REMPI spectra of TCE and PCE were recorded over the wavelength range 305–320 nm. The concentrations of PCE and TCE in the headspace were monitored by measurement of the ionization signal with 315.64- and 310.48-nm excitation for PCE and TCE, respectively. Calibration curves yielded a linear range of …

Geminal Model Chemistry Ii. Perturbative Corrections, Vitaly A. Rassolov, Feng Xu, Sophya Garashchuk

Faculty Publications

We introduce and investigate a chemical model based on perturbative corrections to the product of singlet-type strongly orthogonal geminals wave function. Two specific points are addressed (i) Overall chemical accuracy of such a model with perturbative corrections at a leading order; (ii) Quality of strong orthogonality approximation of geminals in diverse chemical systems. We use the Epstein–Nesbet form of perturbation theory and show that its known shortcomings disappear when it is used with the reference Hamiltonian based on strongly orthogonal geminals. Application of this model to various chemical systems reveals that strongly orthogonal geminals are well suited for chemical models, …

Bohmian Dynamics On Subspaces Using Linearized Quantum Force, Vitaly A. Rassolov, Sophya Garashchuk

Faculty Publications

In the de Broglie–Bohm formulation of quantum mechanics the time-dependent Schrödinger equation is solved in terms of quantum trajectories evolving under the influence of quantum and classical potentials. For a practical implementation that scales favorably with system size and is accurate for semiclassical systems, we use approximate quantum potentials. Recently, we have shown that optimization of the nonclassical component of the momentum operator in terms of fitting functions leads to the energy-conserving approximate quantum potential. In particular, linear fitting functions give the exact time evolution of a Gaussian wave packet in a locally quadratic potential and can describe the dominant …

Energy Conserving Approximations To The Quantum Potential: Dynamics With Linearized Quantum Force, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

Solution of the Schrödinger equation within the de Broglie–Bohm formulation is based on propagation of trajectories in the presence of a nonlocal quantum potential. We present a new strategy for defining approximate quantum potentials within a restricted trial function by performing the optimal fit to the log-derivatives of the wave function density. This procedure results in the energy-conserving dynamics for a closed system. For one particular form of the trial function leading to the linear quantum force, the optimization problem is solved analytically in terms of the first and second moments of the weighted trajectory distribution. This approach gives exact …

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

President's Message, David J. Stroup

Journal of the South Carolina Academy of Science

No abstract provided.

Scas Officers And Council Members 2004 - 2005

Journal of the South Carolina Academy of Science

No abstract provided.

Bioinformatics: An Undergraduate Research/Teaching Tool., Abhishek Agrawal, Valgene L. Dunham

Journal of the South Carolina Academy of Science

No abstract provided.

Building New Culture Media For Assisted Reproductive Technology., Mary N. Egbuniwe, H. Lee Higdon Iii, William R. Boone

Journal of the South Carolina Academy of Science

No abstract provided.

Characterization Of Microbial Communities In Tce-Contaminated Seep Zone Sediments., Brian A. Nevius, Christopher E. Bagwell, Robin L. Brigmon

Journal of the South Carolina Academy of Science

No abstract provided.

Using Microenvironmental Effects To Increase Loading And Stereoselectivity For Polymer Bound Nabh4 Reagents., James R. Blanton

Journal of the South Carolina Academy of Science

No abstract provided.

Pyridoxamine Traps Intermediates In Lipid Peroxidation Reactions In Vivo: Evidence On The Role Of Lipids In Chemical Modification Of Protein And Development Of Diabetic Complications, Thomas O. Metz, Nathan L. Alderson, Mark E. Chachich, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Maillard or browning reactions between reducing sugars and protein lead to formation of advanced glycation end products (AGEs) and are thought to contribute to the pathogenesis of diabetic complications. AGE inhibitors such as aminoguanidine and pyridoxamine (PM) inhibit both the formation of AGEs and development of complications in animal models of diabetes. PM also inhibits the chemical modification of protein by advanced lipoxidation end products (ALEs) during lipid peroxidation reactions in vitro. We show here that several PM adducts, formed in incubations of PM with linoleate and arachidonate in vitro, are also excreted in the urine of PM-treated animals. The …

Bis[Μ-1,2-Bis(2-Pyridyl)Ethyne-K2N:N']Bis[Aquadinitratocadmium(Ii)], Badruz Zaman Md., Matthew J. Davis, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Two twisted 1,2-bis(2-pyridyl)ethyne ligands bridge two Cd²⁺ centers in the C₂-symmetric title complex, [Cd₂(NO₃)₄(-C₁₂H₈N₂)₂(H₂O)₂]. The bridging ligands arch across one another creating a `zigzag loop' molecular geometry. Two nitrate ions and a water molecule complete the irregular seven-coordinate Cd-atom environment. The dihedral angles between the equivalent pyridyl ring planes of the two independent ligands are 67.2 (1)°. O_water-HO_nitrate hydrogen bonding creates two-dimensional layers parallel to the ab plane.

Formula: [Cd₂(NO₃)₄(C …

Sr3Mgpto6, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Single crystals of the mixed alkaline earth platinate, tristrontium magnesium platinum hexaoxide, Sr₃MgPtO₆, were grown from a KOH flux at 1273 K. The compound adopts the rhombohedral K₄CdCl₆ structure type, featuring chains of face-shared, distorted MgO₆ trigonal prisms (Mg site symmetry 32) and PtO₆ octahedra (Pt site symmetry ) surrounded by columns of Sr²⁺ ions (Sr site symmetry 2).

Semiclassical Dynamics With Quantum Trajectories: Formulation And Comparison With The Semiclassical Initial Value Representation Propagator, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

We present a time-dependent semiclassical method based on quantum trajectories. Quantum-mechanical effects are described via the quantum potential computed from the wave function density approximated as a linear combination of Gaussian fitting functions. The number of the fitting functions determines the accuracy of the approximate quantum potential (AQP). One Gaussian fit reproduces time-evolution of a Gaussian wave packet in a parabolic potential. The limit of the large number of fitting Gaussians and trajectories gives the full quantum-mechanical result. The method is systematically improvable from classical to fully quantum. The fitting procedure is implemented as a gradient minimization. We also compare …

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

President's Message

Journal of the South Carolina Academy of Science

No abstract provided.

Histological Effect Of Ascocotyle Tenuicollis (Digenea: Heterophyidae) Metacercarial Infection On The Heart Of Fundulus Heteroclitus (Teleostei: Cyprinodontidae), Toni Hicks, Edna Steele

Journal of the South Carolina Academy of Science

No abstract provided.

Par Mediation Of Thrombin-Induced Effects On Motoneurons, Nadim Salman, Drew Watkins, Kate Hamel, Lakisha Gadsden, Sarah Funderburk, Victoria Turgeon

Journal of the South Carolina Academy of Science

No abstract provided.

Embryogenesis In The Japanese Medaka, Oryzias Latipes, Laura Harris Harris, Lisa Sims, Roxann Stachiw

Journal of the South Carolina Academy of Science

No abstract provided.