The previously developed particle mesh Ewald method is reformulated in terms of efficient B‐spline interpolation of the structure factors This reformulation allows a natural extension of the method to potentials of the form 1/rp with p≥1 Furthermore, efficient calculation of the virial tensor follows Use of B‐splines in place of Lagrange interpolation leads to analytic gradients as well as a significant improvement in the accuracy We demonstrate that arbitrary accuracy can be achieved, independent of system size N, at a cost that scales as N log(N) For biomolecular systems with many thousands of atoms this method permits the use of Ewald summation at a computational cost comparable to that of a simple truncation method of 10 A or less

A smooth particle mesh Ewald method

6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072

/pdf/quantum-mechanical-continuum-solvation-models-3edv963g14.pdf

Quantum mechanical continuum solvation models.

This article describes the software suite GROMACS (Groningen MAchine for Chemical Simulation) that was developed at the University of Groningen, The Netherlands, in the early 1990s. The software, written in ANSI C, originates from a parallel hardware project, and is well suited for parallelization on processor clusters. By careful optimization of neighbor searching and of inner loop performance, GROMACS is a very fast program for molecular dynamics simulation. It does not have a force field of its own, but is compatible with GROMOS, OPLS, AMBER, and ENCAD force fields. In addition, it can handle polarizable shell models and flexible constraints. The program is versatile, as force routines can be added by the user, tabulated functions can be specified, and analyses can be easily customized. Nonequilibrium dynamics and free energy determinations are incorporated. Interfaces with popular quantum-chemical packages (MOPAC, GAMES-UK, GAUSSIAN) are provided to perform mixed MM/QM simulations. The package includes about 100 utility and analysis programs. GROMACS is in the public domain and distributed (with source code and documentation) under the GNU General Public License. It is maintained by a group of developers from the Universities of Groningen, Uppsala, and Stockholm, and the Max Planck Institute for Polymer Research in Mainz. Its Web site is http://www.gromacs.org.

/pdf/gromacs-fast-flexible-and-free-15aazpel5u.pdf

GROMACS: Fast, flexible, and free

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

At present, algorithms used in nuclear medicine to reconstruct single photon emission computerized tomography (SPECT) data are usually based on one of two principles: filtered back projection and iterative methods. In this paper a different algorithm, applying an artificial neural network (multilayer perceptron) and error backpropagation as training method are used to reconstruct transaxial slices from SPECT data. The algorithm was implemented on an Elscint XPERT workstation (i486,50 MHz) used as routine digital image processing tool in our departments. Reconstruction time for a 64×64 matrix is approximately 10 seconds per transaxial slice. The algorithm has been validated by a mathematical model and tested on heart and Jaszczak phantoms. The very first results show in comparison with filtered back projection an improvement in image quality.

Reconstruction Of SPECT Data Using an Artificial Neural Network

In this paper a combined neutron scattering and quantum simulation study of the collective dynamics in liquid Ne-D_{2} mixtures, at a temperature of T=30K and in the wave-vector transfer range 4 nm^{-1}<q<51nm^{-1}, is presented. Two D_{2} concentrations are investigated, one close to 25% molar and the other close to 50% molar, together with pure Ne. The dynamic structure factor for the centers of mass of the two molecular species is extracted from the neutron scattering data and subsequently compared with that obtained from three different quantum simulation methods, such as ring polymer molecular dynamics and two slightly different versions of the Feynman-Kleinert approach. A general agreement is found, even though some discrepancies both among simulations, and between simulations and experimental data, can be observed. In order to clarify the physical meaning of the present spectroscopic results, an analysis of the longitudinal current spectral maxima is carried out showing the peculiarities of the D_{2} center-of-mass dynamics in these mixtures. A comparison with the centroid molecular dynamics results obtained for the D_{2} center-of-mass self-dynamics in the same liquid mixtures is finally proposed.

Microscopic collective dynamics in liquid neon-deuterium mixtures: Inelastic neutron scattering and quantum simulations.

We have measured the center-of-mass structure factor S(k) of liquid para-hydrogen by neutron diffraction, using the D4C diffractometer at the Institute Laue Langevin, Grenoble, France The present determination is at variance with previous results obtained from inelastic neutron scattering data, but agrees with path integral Monte Carlo simulations

https://arxiv.org/pdf/cond-mat/0209239.pdf

Microscopic structure of liquid hydrogen: a neutron diffraction experiment

Ewald summation of electrostatic interactions of systems with finite extent in two of three

The inner-level and valence-band X-ray photoelectron spectra of TiC–NbC solid solutions have been studied. The TiLα, NbLβ2,15, and CKα X-ray emission spectra and the valence-band photoelectron spectra were fitted to a single energy scale relative to the Fermi level, and the results of the fitting are analyzed. It is shown that formation of the electronic structure of these mixed carbides is strongly affected by the variation of the lattice parameters and also by the mutual effects of the Ti and Nb atoms on charge redistribution between them.

Martin Neumann

Papers

Reconstruction Of SPECT Data Using an Artificial Neural Network

Microscopic collective dynamics in liquid neon-deuterium mixtures: Inelastic neutron scattering and quantum simulations.

Microscopic structure of liquid hydrogen: a neutron diffraction experiment

Ewald summation of electrostatic interactions of systems with finite extent in two of three

X-RAY PHOTOELECTRON SPECTRA IN TiC-NbC SOLID SOLUTIONS