Molecular Origins of the High-Performance Nonlinear Optical Susceptibility in a Phenolic Polyene Chromophore: Electron Density Distributions, Hydrogen Bonding, and ab Initio Calculations

2013 ◽  
Vol 117 (18) ◽  
pp. 9416-9430 ◽  
Author(s):  
Tze-Chia Lin ◽  
Jacqueline M. Cole ◽  
Andrew P. Higginbotham ◽  
Alison J. Edwards ◽  
Ross O. Piltz ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Density ◽  
High Performance ◽  
Nonlinear Optical ◽  
Nonlinear Optical Susceptibility ◽  
Density Distributions ◽  
Optical Susceptibility

scholarly journals A lattice-dynamical refinement approach based on periodic ab-initio calculations

2014 ◽  
Vol 70 (a1) ◽  
pp. C1441-C1441
Author(s):  
Anders Madsen
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Density ◽  
High Performance ◽  
Normal Modes ◽  
Thermal Motion ◽  
Model Systems ◽  
Model Parameters ◽  
Large Area ◽  
X Ray

The use of synchrotron radiation and large area detectors has increased the quality and quantity of X-ray and neutron diffraction data within the last decades. These advances call for new and better approaches to model and to interpret the data. Elastic X-ray diffraction corresponds to the Fourier transform of the thermally averaged electron density in the unit cell. This density is normally approximated as the convolution of a sum of static atomic densities and the thermal motion of the individual atoms. The static densities and thermal motion are equally important: Together they conform the entire model refined against a single set of measured data, and they must both be modeled correctly, or neither is. The advent of high-performance computers has made it feasible to obtain lattice-dynamical models based on periodic quantum-mechanical calculations, to describe the concerted motion of atoms and molecules through the crystal. Our recent calculations of Debye-Waller factors based on periodic ab-initio calculations for various molecular test systems [1] has prepared the ground for proposing the refinement of quantum-mechanically derived normal modes of vibration against diffraction experiments. As opposed to the standard approach using independent atomic motion, some of the advantages and possibilities that emerge are: 1. A physically reasonable picture of the molecular motion in the crystal. 2. Refinement against data obtained at multiple temperatures in a common model. 3. Modeling thermal diffuse scattering. 4. Reduction of the number of model parameters. 5. Anisotropic motion of H atoms. The approach is computationally expensive, but may prove useful for electron density studies, studies of thermal effects in crystals, i.e. studies of thermochromic and thermoelectric compounds, solid-state phase-transitions and to derive thermodynamic properties, e.g. free energies of polymorphic crystals. We will introduce the method and present some first results for model systems.

N-Heterocyclic Carbenes and Parent Cations: Acidity, Nucleophilicity, Stability, and Hydrogen Bonding-Electrochemical Study and Ab Initio Calculations

2016 ◽  
Vol 3 (7) ◽  
pp. 1133-1141 ◽  
Author(s):  
Marta Feroci ◽  
Isabella Chiarotto ◽  
Francesca D'Anna ◽  
Fabrizio Gala ◽  
Renato Noto ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Heterocyclic Carbenes ◽  
Electrochemical Study
Sign in / Sign up

Export Citation Format

Share Document