نتایج جستجو برای: مطالعه dft

تعداد نتایج: 297438  

2016
Selvarengan Paranthaman

In the present investigation, the results of extensive benchmarking study of density functional theory (DFT) methods on some catalytically important metal dimers have been reported. The calculations were carried out on Al2, Ti2, V2, Cr2, Mn2, Fe2, Co2, Ni2, Cu2, and Zn2 using DFT functionals such as GGA, meta GGA, hybrid meta GGA along with recently developed Minnesota functionals. The bond len...

2011
Chunming Wu Baohua Qiang Xianchun Zou

Deep web provides tremendous structured data with high quality. In order to retrieve deep web data, one important task is to classify the domains of deep web automatically. In this paper, an approach based on domain feature text (DFT) is presented to classify the deep web. In the phase of DFT selection, a semantic abstract method based on ontology knowledge and a quantitative criteria for DFT s...

2008
Richard C. Hendriks Jesper Jensen Richard Heusdens

DFT domain based noise reduction algorithms can be effective for noise reduction in various speech processing applications. In general these algorithms apply a noise-PSD dependent estimator to the noisy speech DFT coefficients in order to estimate the clean speech DFT coefficients. Since the noise PSD is unknown in advance, estimation is one of the crucial elements of such a noise reduction sys...

2017
W. H. Brito S. Choi

We investigate the normal state of the superconducting compound PuCoGa5 using the combination of density functional theory (DFT) and dynamical mean field theory, with continuous time quantum Monte Carlo as the impurity solver, and the DFT+Gutzwiller/rotationally invariant slave boson method. With both methods we find a strong tendency of the orbitals to differentiate. The more accurate DFT+DMFT...

Journal: :Journal of the American College of Cardiology 2012
N A Mark Estes

In 3 decades of clinical use of the implantable cardioverter-defibrillator (ICD), defibrillation threshold (DFT) testing has remained an integral part of the implantation procedure. The prevailing rationale for the routine evaluation of DFTs has been to ensure appropriate sensing of ventricular fibril-lation, system integrity, and effective defibrillation (1–3). Early ICD systems using monophas...

Journal: : 2022

اندازه‌گیری پرتو گاما در زمینه‌های مختلف تحقیقاتی نیازمند آشکارسازهای کارآمد است. زمینه دزیمتری فوتون آشکارساز جرقه‌ای NaI(Tl) به عنوان یکی از سوسوزن معدنی (غیرآلی)، علت دارا بودن مقدار بالای نور خروجی بسیار حایز اهمیت این پژوهش سعی گردیده است، با کمک کد مونت‌کارلو (MCNPX) مقدمات مشخصه‌یابی توسط و بهره‌گیری روش‌های متفاوت محاسبه دز (تالی‌های 6F، 4*F، 6+F 8*F) انجام شود. طور معمول، یک تابش (شمار...

پایان نامه :دانشگاه تربیت معلم - تهران - دانشکده شیمی 1390

در این مطالعه تجزیه فوتوکاتالیستی فنول، اورتومتیل فنول و اورتوآمینوفنول با روشهای نیم تجربی و dft بررسی شد. ابتدا مواد اولیه و محصولات با روش pm3 بهینه سازی شدند و سپس ساختار حالت گذار واکنش ها با روش pm3 بدست آمد. آنتالپی تشکیل مواد اولیه، محصولات، حالت گذار و آنتالپی واکنش ها با روش pm3 محاسبه شد. انرژی همه ترکیبات و انرژی فعالسازی واکنش ها با روش 6-31g(d) /dft محاسبه شد. ساختار حالت گذار واک...

2000
Ping Tak Peter Tang

The Fast Fourier Transform (FFT) algorithm that calculates the Discrete Fourier Transform (DFT) is one of the major breakthrough in scientific computing and is now an indispensable tool in a vast number of fields. Unfortunately, software that provide fast computation of DFT via FFT differ vastly in functionality as well as uniformity. A widely accepted Applications Programmer Interface (API) fo...

2009
L. Lehtovaara

The density functional theory (DFT) has become the workhorse in electronic structure calculations. Its success derives from the ability to produce accurate results with reasonable computational effort. The drawback of the DFT is that in principle it is bound to the ground-state properties. However, the time-dependent DFT (TDDFT) extends the applicatibility of the DFT to excited states. In recen...

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