Atomic origins of molecular polarizabilities

1996 ◽  
Vol 74 (6) ◽  
pp. 1131-1138 ◽  
Author(s):  
Keith E. Laidig
Keyword(s):  
Carbon Monoxide ◽  
Spatial Distribution ◽  
Quantum Mechanics ◽  
Key Words ◽  
Electric Fields ◽  
Polarizability Tensor ◽  
Electronic Charge ◽  
Field Gradients ◽  
Carbon Sulfide ◽  
Molecular Polarizabilities

We demonstrate that the multipole polarizability tensors of a molecule are expressible as a sum of atomic contributions, each of which is based upon the change in the spatial distribution of electronic charge within each atom resulting from the application of electric fields and field gradients. The use of the spatially defined atoms of subsystem quantum mechanics correctly partitions molecular polarizabilities into physically meaningful atomic contributions. It is shown that the origin of any molecular polarizability tensor may be understood from an investigation of these contributions and the general expressions for the summation of atomic components to yield molecular polarizabilities are presented. Their use is demonstrated by the construction and investigation of the axial components of the dipole–dipole dipole–quadrupole, and quadrupole–quadrupole polarizability tensors of carbon monoxide and carbon sulfide. Key words: atomic polarizabilities, atoms-in-molecules, molecular polarizabilities.

scholarly journals Top-down estimation of carbon monoxide emissions from the Mexico Megacity based on FTIR measurements from ground and space

2012 ◽  
Vol 12 (11) ◽  
pp. 29915-29965 ◽  
Author(s):  
W. Stremme ◽  
M. Grutter ◽  
C. Rivera ◽  
A. Bezanilla ◽  
A. R. Garcia ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Spatial Distribution ◽  
Mexico City ◽  
Emission Flux ◽  
Top Down ◽  
Solar Absorption ◽  
Surface Emission ◽  
The Difference ◽  
Anthropogenic Pollutant ◽  
Total Column

Abstract. Continuous carbon monoxide (CO) total column densities above the UNAM campus in Mexico City have been derived from solar absorption infrared spectroscopic measurements since October 2007. Its diurnal evolution is used in the present study in conjunction with other ground-based and satellite data to develop a top-down emission estimate of the annual CO emission of the Mexico City Metropolitan Area (MCMA). The growth-rate of the total column around noon under low ventilation conditions is calculated and allows us to derive the average surface emission-flux at UNAM, while similar measurements taken at the edge of the MCMA in Tecámac provides information on background CO levels in the Mexico basin. Based on 3 yr of measurements, CO column measurements from the IASI satellite instrument are used to reconstruct the spatial distribution of this anthropogenic pollutant over the MCMA. The agreement between the measured columns of the satellite and ground-based measurements is excellent, particularly when a comparison strategy based on time-displaced air masses is used. The annual emission of the Mexico Megacity is estimated to be (2.15 ± 0.5) Tg yr−1 for the year 2008, while the official inventory for that year reported 1.6 Tg yr−1. The difference is slightly higher than the conservative uncertainty estimated in this work suggesting that the emission might be underestimated by the conventional bottom-up method. A larger discrepancy is found in the spatial distribution of the emissions, when comparing the emission flux over UNAM (derived from the ground-based measurement) with that of the inventory integrated over a representative area. The methodology presented here represents a new and useful strategy to evaluate the contribution of megacities to the global anthropogenic gas emissions. Additionally, three different strategies to compare ground and space-based measurements above an inhomogeneous and strongly contaminated area like Mexico City are presented and discussed.

Ab initio Calculations of the Electric Field Gradients in Solids in Relation to the Charge Distribution

1992 ◽  
Vol 47 (1-2) ◽  
pp. 197-202 ◽  
Author(s):  
Karlheinz Schwarz ◽  
Peter Blaha
Keyword(s):  
Electric Field ◽  
Electronic Charge ◽  
Full Potential ◽  
Electric Field Gradients ◽  
Electronic Charge Density ◽  
Polarization Effects ◽  
Field Gradients ◽  
Band Structure Calculations ◽  
Flapw Method ◽  
Structure Calculations

AbstractA first principles method for the computation of electric field gradients (EFGs) is illustrated for various solids. This scheme is based on self-consistent energy band-structure calculations by the full potential linearized augmented plan wave (FLAPW) method which provides the electronic charge density including all polarization effects. By numerically solving Poisson's equation we obtain the Coulomb potential in a form which allows to compute the EFG directly. Our method is demonstrated for insulators (Cu2O), metals (hcp-Zn), supercondutors (YBa2Cu3O7 ) and molecular crystals (Cl2, Br2 , I2).

scholarly journals Probing Electric Fields in Protein Cavities by Using the Vibrational Stark Effect of Carbon Monoxide

2005 ◽  
Vol 88 (3) ◽  
pp. 1978-1990 ◽  
Author(s):  
Hartwig Lehle ◽  
Jan M. Kriegl ◽  
Karin Nienhaus ◽  
Pengchi Deng ◽  
Stephanus Fengler ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Electric Fields ◽  
Stark Effect

Spatial distribution of active sites on a ferroelectric PbTiO3 photocatalyst for photocatalytic hydrogen production

2017 ◽  
Vol 198 ◽  
pp. 463-472 ◽  
Author(s):  
Rengui Li ◽  
Yue Zhao ◽  
Can Li
Keyword(s):  
Spatial Distribution ◽  
Hydrogen Production ◽  
Solar Energy ◽  
Energy Conversion ◽  
Electric Fields ◽  
Charge Separation ◽  
Active Sites ◽  
Solar Energy Conversion ◽  
Photogenerated Electrons ◽  
The Right

The separation of photogenerated charge carries is a challenging issue in artificial photocatalyst systems for solar energy conversion. It has been reported that spatial charge separation can take place between different facets of semiconductor-based crystals with regular morphology and facets, which could be used to rationally deposit cocatalysts on the right facets. However, the spatial separation of photogenerated electrons and holes is still a big challenge for a particulate photocatalyst without regular morphology and specific facets. In this work, we demonstrated that photogenerated electrons and holes can be regularly separated on ferroelectric PbTiO3 photocatalyst even without regular morphology and facets. The reduction cocatalyst and oxidation cocatalyst could be selectively formed on different sites via an in situ photochemical deposition method. It is found that the photoactivity and hydrogen production for PbTiO3 with spatially separated dual-cocatalysts is remarkably enhanced to more than 100 times greater compared to native PbTiO3, which is much higher than that the case of dual-cocatalysts with a random distribution. The intrinsic electric fields and spontaneous electric polarization in the bulk of PbTiO3 are proposed to play important roles in the spatial distribution of active sites on irregular PbTiO3 particles. Our work emphasizes the essential roles of two important factors, efficient charge separation strategy and the location of dual-cocatalysts on the right sites, to construct integrated artificial photocatalyst systems for solar energy conversion.

Underwriting information-theoretic accounts of quantum mechanics with a realist, psi-epistemic model

2016 ◽  
Vol 14 (04) ◽  
pp. 1640007
Author(s):  
W. M. Stuckey ◽  
Michael Silberstein ◽  
Timothy McDevitt
Keyword(s):  
Quantum Mechanics ◽  
Null Space ◽  
Lattice Gauge Theory ◽  
Transition Amplitude ◽  
Space Time ◽  
Difference Matrix ◽  
Information Theoretic ◽  
Field Gradients ◽  
Row Space ◽  
Epistemic Model

We propose an adynamical interpretation of quantum theory called Relational Blockworld (RBW) where the fundamental ontological element is a 4D graphical amalgam of space, time and sources called a “spacetimesource element.” These are fundamental elements of space, time and sources, not source elements in space and time. The transition amplitude for a spacetimesource element is computed using a path integral with discrete graphical action. The action for a spacetimesource element is constructed from a difference matrix K and source vector J on the graph, as in lattice gauge theory. K is constructed from graphical field gradients so that it contains a non-trivial null space and J is then restricted to the row space of K, so that it is divergence-free and represents a conserved exchange of energy–momentum. This construct of K and J represents an adynamical global constraint between sources, the spacetime metric and the energy–momentum content of the spacetimesource element, rather than a dynamical law for time-evolved entities. To illustrate this interpretation, we explain the simple EPR-Bell and twin-slit experiments. This interpretation of quantum mechanics constitutes a realist, psi-epistemic model that might underwrite certain information-theoretic accounts of the quantum.

scholarly journals Space-toponymical features of forests of Kirovohrad region of Ukraine

2015 ◽  
pp. 87-94
Author(s):  
Аndriy Domaranskiy ◽  
Yelyzaveta Мilenina
Keyword(s):  
Spatial Distribution ◽  
Key Words ◽  
Information Sources ◽  
Research Data ◽  
Research Areas ◽  
Generalized Information ◽  
Forested Areas ◽  
History Of ◽  
The Moment ◽  
Qualitative Changes

The article contains a brief history of toponymical research in Ukraine. The reasons of the growing relevance of the question of space-toponymical inventory of forests in general and particularly in Kirovograd region are analysed and systematised in the article. The main toponymical research areas and the bibliography have been considered. The special attention is focused on the features of Kirovohrad region toponymy study. The problems of toponymical and spatial research of Kirovohrad region forests features are analysed. The methodology of carrying out space-toponymical inventory of forests was submitted. The different age’s maps and specialized cartographic works were investigated in details for gathering information discovering quantitative and qualitative changes in the system of drymonyms in research region. A large amount of lost and changed place names of wooded areas was restored. The obtained database of drymonyms has been analysed for detecting changed, varied and dual wood names and also saved authentic toponyms. The research data were presented in the detailed statistics on forests of Kirovohrad region and their names. The main space-toponymical features and trends of forested areas in Kirovohrad region were identified. The schematic map, that contains generalized information about spatial distribution of Kirovohrad region forests, there real outlines (by the moment of creating the map) and there toponyms – authentic and changed with references to information sources, was signed. Key words: space-toponymical features of forests, space-toponymical inventory of forests, toponymy, toponymic, drymonyms, toponyms, forested areas, forests of Kirovohrad region.

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