نتایج جستجو برای: dft method

تعداد نتایج: 1645998  

2014
Hajime Hirao Nandun Thellamurege Xi Zhang

The past decades have seen an explosive growth in the application of density functional theory (DFT) methods to molecular systems that are of interest in a variety of scientific fields. Owing to its balanced accuracy and efficiency, DFT plays particularly useful roles in the theoretical investigation of large molecules. Even for biological molecules such as proteins, DFT finds application in th...

2010
V. L. Chevrier S. P. Ong G. Ceder

We compare the accuracy of conventional semilocal density functional theory DFT , the DFT+U method, and the Heyd-Scuseria-Ernzerhof HSE06 hybrid functional for structural parameters, redox reaction energies, and formation energies of transition metal compounds. Conventional DFT functionals significantly underestimate redox potentials for these compounds. Zhou et al. Phys. Rev. B 70, 235121 2004...

پایان نامه :وزارت بهداشت، درمان و آموزش پزشکی - دانشگاه علوم پزشکی و خدمات بهداشتی درمانی تهران 1354

چکیده ندارد.

A. Rostami H. Baghban M. Dolatyari M. H. Majles Ara M. Hatami 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...

Journal: :Physical chemistry chemical physics : PCCP 2012
Prabha Jayapal Gopalan Rajaraman

An energetics-spectroscopic approach based on DFT method reveals that the active site structure of AurF has {Fe(III)(2)O} central core with one protonated terminal glutamate.

2015
Huiyue Yang Yaqing Tu Haitao Zhang Ming Li

This paper investigates spectrum leakage influence on the performance of discrete Fourier transform (DFT) based phase difference measurement and proposes a novel method with spectrum leakage considered. In the proposed method, spectrum is firstly corrected by interpolation algorithm to remove the influence of short range leakage. To avoid negative frequency interference caused by the long range...

Journal: :The Journal of chemical physics 2014
Alessandro Genova Davide Ceresoli Michele Pavanello

By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn-Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline so...

Journal: :Signal Processing 2015
Weihua Zheng Kenli Li Keqin Li

Discrete Fourier transform (DFT) is used widely in almost all fields of science and engineering, and is generally calculated using the fast Fourier transform (FFT) algorithm. In this paper, we present a fast algorithm for efficiently computing a DFT of size 3 2. The proposed algorithm decomposes the DFT, obtaining one length-2 unscaled sub-DFT and two length-2 sub-DFTs scaled by constant real n...

2006
Selçuk Baktir Berk Sunar

We introduce an efficient method for computing Montgomery products of polynomials in the frequency domain. The discrete Fourier transform (DFT) based method originally proposed for integer multiplication provides an extremely efficient method with the best asymptotic complexity, i.e. O(m log m log log m), for multiplication of m-bit integers or (m−1)st degree polynomials. Unfortunately, the DFT...

Journal: :Digital Signal Processing 2008
Magdy T. Hanna Nabila P. Attalla Seif M. Waleed Abd El Maguid Ahmed

The recent emergence of the discrete fractional Fourier transform (DFRFT) has caused a revived interest in the eigenanalysis of the discrete Fourier transform (DFT) matrix F with the objective of generating orthonormal Hermite-Gaussian-like eigenvectors. The Grünbaum tridiagonal matrix T – which commutes with matrix F – has only one repeated eigenvalue with multiplicity two and simple remaining...

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