نتایج جستجو برای: dft method

تعداد نتایج: 1645998  

2009
Jürgen Gräfenstein Dieter Cremer

The self-interaction error (SIE) plays a central role in density functional theory (DFT) when carried out with approximate exchange-correlation functionals. Its origin, properties, and consequences for the development of standard DFT to a method that can correctly describe multi-reference electron systems by treating dynamic and non-dynamic electron correlation on an equal footing, is discussed...

Journal: :CoRR 2013
Vilnis Liepins

This summary of the doctoral thesis [8] is created to emphasize the close connection of the proposed spectral analysis method with the Discrete Fourier Transform (DFT), the most extensively studied and frequently used approach in the history of signal processing. It is shown that in a typical application case, where uniform data readings are transformed to the same number of uniformly spaced fr...

Journal: :journal of physical and theoretical chemistry 0
mohammad mahdi akbarzadeh building chemical engineering, setoodeh bana co., jomhori st., p.o. box 13187-63715, tehran, iran khirollah mehrani department of chemistry, ardabil branch, islamic azad university, p.o. box 56157-31567, ardabil, iran shahriar ghammamy faculty of sciences, science and research branch, islamic azad university, p.o. box 14778-93855, tehran, iran vahideh hadigheh rezvan department of chemistry, imam khomeini international university, p.o. box 34148 - 96818 qazvin, iran

compound (n,n-bis (salicylidene) 1,2-diaminophenylene) was prepared by condensation of ethanolsolution of 2-hydroxybanzaldehyde and 1,2-diaminophenylene. the compound was characterized by1h nmr, infrared spectroscopy (ft-ir) data and analytical data. the geometrical parameters andenergies have been obtained from density functional theory (dft) b3lyp method and hartree-fock (hf) method with 3-21...

2006
Alexander Hinneburg Dirk Habich Marcel Karnstedt

Sensor data have become very huge and single measures are produced at high rates, resulting in streaming sensor data. In this paper, we present a new mining tool called Online DFT, which is particularly powerful for estimating the spectrum of a data stream. Unique features of our new method include low update complexity with high-accuracy estimations for very long periods, and the ability of lo...

2000
Vladimı́r Sychrovský Jürgen Gräfenstein Dieter Cremer

For the first time, a complete implementation of coupled perturbed density functional theory ~CPDFT! for the calculation of NMR spin–spin coupling constants ~SSCCs! with pure and hybrid DFT is presented. By applying this method to several hydrides, hydrocarbons, and molecules with multiple bonds, the performance of DFT for the calculation of SSCCs is analyzed in dependence of the XC functional ...

2009
Edward F.C. Byrd Cary F. Chabalowski

The performance of density functional theories (DFT) in predicting structural parameters for six conventional energetic materials (EM) over various degrees of compression was examined for a wide range of pressures. The systems studied were nitromethane, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), cyclotrimethylenetrinitramine (RDX), 2,4,6,8,10,12hexanitrohexaazaisowurzitane (CL-20), 2...

Journal: :The Journal of chemical physics 2014
Daniel Neuhauser Roi Baer Eran Rabani

We develop a method in which the electronic densities of small fragments determined by Kohn-Sham density functional theory (DFT) are embedded using stochastic DFT to form the exact density of the full system. The new method preserves the scaling and the simplicity of the stochastic DFT but cures the slow convergence that occurs when weakly coupled subsystems are treated. It overcomes the spurio...

Journal: :international journal of nanoscience and nanotechnology 2012
m. hatami m. h. majles ara a. rostami m. dolatyari m. mahmudi

well-defined crystalline pbse nanocubes and nanospheres have been synthesized through a simple hydrothermal method by using pb2+- edta and pb2+- oleylamine complexes at 180°c for different reaction times. composition and morphology of the samples have been characterized by means of xrd and sem. gradual release process of pb2+ from pb2+-edta and pb2+-oleylamine complexes can adjust the growth ra...

2001
Hlaing Minn Vijay K. Bhargava

A time-domain based channel estimation for OFDM system with pilot-data multiplexed scheme is investigated. As an approximation to linear minimum mean square estimator (LMMSE), a time-domain based channel estimation is proposed where intra-symbol time-averaging and most significant channel taps selection are applied. The relation and differences of the proposed method to DFT-based LMMSE methods ...

Journal: :The journal of physical chemistry letters 2015
Min-Cheol Kim Hansol Park Suyeon Son Eunji Sim Kieron Burke

Density-corrected DFT is a method that cures several failures of self-consistent semilocal DFT calculations by using a more accurate density instead. A novel procedure employs the Hartree-Fock density to bonds that are more severely stretched than ever before. This substantially increases the range of accurate potential energy surfaces obtainable from semilocal DFT for many heteronuclear molecu...

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