Scientific Program

Conference Series Ltd invites all the participants across the globe to attend 4th International Conference on Physical and Theoretical Chemistry Dublin, Ireland.

Day 2 :

OMICS International Physical Chemistry 2017 International Conference Keynote Speaker Wai-Yim Ching photo
Biography:

Dr. Wai-Yim Ching is a Distinguished Curators’ Professor of Physics at the University Missouri-Kansas City, USA. He leads the Electronic Structure Group (ESG) in the Department of Physics and Astronomy. His research focuses on condensed matter theory and computational materials science using first-principles methods. With more than 40 years of experience, he is an author or co-author of over 410 journal articles in diverse areas related to materials and with a Google Scholar Citation H-index 64.  He is an Academician of World Ceramic Academy, a Fellow of the American Ceramic Society and the American Physical Society. He is an Associate Editor of the Journal of the American Ceramic Society and is on the Editorial Board of Nature Scientific Reports.

Abstract:

Statement of the problem: Metal-organic frameworks (MOFs) materials have attracted immense attention from diverse disciplines of chemistry, physics, engineering, material sciences, biological and biomedical sciences. Zeolitic imidazolate framework (ZIF) is an important member of MOF with a network topologies analogous to silica. In the network, the corner-sharing SiO4 tetrahedra are replaced by MN4 tetrahedra (M = metal, Zn in this work) linked by imidazolate (IM) (C3N2H3)-anions. The chemically tunable porosities of ZIFs are pivotal for many of their potential application. There exist a large number of crystalline ZIFs with well-defined zeolite structures, the emerging category of non-crystalline or amorphous ZIF (a-ZIF) is of particular interest. The a-ZIF can be viewed as a model system for understanding the general features and properties of a novel hybrid inorganic/organic glass with no long range order (LRO) but with well-preserved short range order (SRO). We have recently constructed a large a-ZIF mode and studied its electronic structure, inter-atomic bonding and optical properties. In this talk I present further study of the deformation behavior of this interesting material by applying step-wise homogenous compression and extension with strains respectively up to -0.30 and +0.30. The data for stress vs strain at each step are fully analyzed including mechanical properties. It shows that a-ZIF is a super-soft materials with intricate properties that have not been seen before. The origin of this behavior is explained by detailed electronic structure and bonding investigation.  Conclusion and significance: Our investigation shows that a-ZIF belongs to a class of super-soft materials with some intricate properties previous unknown. Additional large-scale accurate simulations may reveal other properties for potential applications especially in the soft covalent organic framework (COF) materials.

 

OMICS International Physical Chemistry 2017 International Conference Keynote Speaker Werner Paulus photo
Biography:

Werner Paulus is exploring low temperature oxygen diffusion mechanisms in transition metal oxides. Oxygen doping, via topotactic reaction mechanisms while proceeding at ambient temperature is a powerful tool to access structural and electronic complexity in a controlled way. It also allows to better explore the underlying diffusion mechanisms on an atomic scale, having huge importance in solid state ionics, e.g. for the optimisation of battery materials, fuel cell membranes/electrolytes or sensors. Research activities cover synthesis methods from powder to large single crystals and to explore oxygen intercalation reactions in especially dedicated electrochemical cells on single crystals and polycrystalline electrodes by neutron and X-ray diffraction (synchrotron & laboratory), spectroscopy (XAFS, Raman, INS, IXS, NMR) combined with 18O/16O oxygen isotope exchange reactions and sophisticated data analysis (Maximum Entropy, twinning).

Abstract:

Since more than two decades, Transition Metal Oxides with strongly correlated electrons are intensively studied due their interesting physical properties. This includes colossal magnetoresistance (CMR) where huge variations in resistance are achieved just by small changes in the applied magnetic field, or high temperature superconductivity (HTC) to name two of them [3-6]. These materials are characterized by the existence of several competing states such as charge, spin and orbital ordering, interacting in a synergetic way and leading to fairly complex phase diagrams. Thereby the physical properties can be tuned in a wide range via hole doping, e.g. by cation substitution as is the case for RE2-xSrxMO4.

An alternative way of hole doping presents oxygen intercalation, generally proceeding at ambient temperature via a topotactic oxygen uptake along shallow potential diffusion pathways. Contrary to the cation substitution, requiring high reaction temperatures, oxygen intercalation reactions allow the controlled synthesis of strongly correlated oxides far away from thermodynamic equilibrium, essentially resulting in kinetically stabilized and thus metastable phases.

Low temperature reactivity of solids may thus be used as a concept, to investigate the limits of available structural and electronic complexity in transition metal oxides. The reaction pathway to insert oxygen at low temperatures in solid oxides becomes a decisive parameter to tune correlations, leading to extremely complex phase relations as physical and structural properties are not only depending on the overall stoichiometry, but decisively on the sample history. Taking these oxides as oxygen ‘sponges’ operating at low reaction temperatures down to ambient, structural and electronic correlation lengths could then be influenced by the reaction conditions and kinetics. We here discuss here the challenges, low temperature solid state reactivity implies for the synthesis of new complex oxides but equally the current understanding of the relying oxygen diffusion mechanisms, having a huge fundamental and technological interest.

Pr2NiO4.25: Representations of the NiO6 isosurfaces (left) for indicate the anharmonic double potential of the apical oxygen atoms present at 673 K, obtained from single crystal neutron diffraction and Maximum Entropy Analysis. The large anisotropic displacements of the apical oxygen atoms along [110] directly point towards the interstitial oxygen sites, forming a shallow oxygen diffusion pathway which is dynamically activated.

OMICS International Physical Chemistry 2017 International Conference Keynote Speaker Per Jensen photo
Biography:

Per Jensen is professor of theoretical chemistry at the University of Wuppertal, Germany. His research interests lie in the border area between high-resolution molecular spectroscopy and quantum chemistry. He develops and applies methods for the accurate simulation of rotation-vibration spectra of small molecules, mostly of astrochemical and/or atmospheric interest. He is particularly interested in the application of molecular symmetry to facilitate the solution of nuclear-motion problems. Recently, he has worked extensively on interactions between electronic states (the Renner effect), the characterization of rovibrational energy clusters at high rotational excitation, and extremely flexible (structureless) molecules. He is author or co-author of about 200 publications.

Abstract:

Traditionally, molecules are theoretically described as near-static structures rotating in space. Vibrational motion causing small structural deformations induces a perturbative treatment of the rotation-vibration interaction. This treatment fails in highly flexible molecules, where all vibrational motions have amplitudes comparable in size to the linear dimensions of the molecule. An example is protonated methane (CH5+). For these molecules, customary theory fails to simulate reliably even the low-energy spectrum. Within the traditional view of rotation and vibration being near-separable, rotational and vibrational wavefunctions are symmetry classified separately in the molecular symmetry (MS) group. All MS groups discussed so far are isomorphic to subgroups of the special orthogonal group in three dimensions SO(3). This leads to a group theoretical foundation of the technique of equivalent rotations. The group G240 (the MS group of protonated methane) represents, to the best of our knowledge, the first example of an MS group which is not isomorphic to a subgroup of SO(3). Because of this, a separate symmetry classification of vibrational and rotational wavefunctions becomes impossible in this MS group, consistent with the fact that a decoupling of vibrational and rotational motion is impossible. The talk will discuss the consequences of this and propose an alternative description making use of the fact that G240 and SO(3) are both subgroups of the group SO(5) of rotations in five-dimensional space. We take SO(5) to be a near-symmetry group for CH5+ and develop a theoretical model that successfully explains recent experimental observations of rotation-vibration transitions in cold CH5+. Two of the vibrational degrees of freedom are essentially free and, in an initial approximation, these vibrations are combined with the “usual” rotation in 3D space with the resulting motion being viewed as free rotation in 5D space, consistent with the symmetry group SO(5).

Figure 1: The effect of the proton permutation (15432) on a CH5+ ion. It rotates the quantization axis z and so the customary technique of equivalent rotations cannot be applied.