نتایج جستجو برای: density functional theory method

تعداد نتایج: 3067115  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی امیرکبیر(پلی تکنیک تهران) - دانشکده فیزیک 1385

در اینجا با بکار بردن نظریه تابعی چگالی و روش پدیده شناسی در مخلوط 3he-4heبعنوان یک سیستم دوتایی بوزون-فرمیون توانستیم ویژگی های ترمودینامیک 3hc-4hcدر دمای صفر مطلق بدست آوریم. مطالعه مخلوط های رقیق 3he-4he در دماهای بسیار پایین موضوع مورد توجه اغلب دانشمندان تجربی و تئوری در گذشته بوده است. چندین کمیت فیزیکی از نظر تجربی مانند فشار اسمزی، گرمای مخلوط شدن و قابلیت حل پذیری 3hcدر 3hcمشخص شده اند...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2001
M B Sweatman

The adsorption of a Lennard-Jones fluid in an ideal slit pore is studied using weighted density functional theory. The intrinsic Helmholtz free-energy functional is separated into repulsive and attractive contributions. Rosenfeld's accurate fundamental measure functional is employed for the repulsive functional while another weighted density functional method is employed for the attractive func...

2008
L. L. Boyer H. T. Stokes M. M. Ossowski M. J. Mehl

We describe a computational method based on density functional theory in which the total electronic density is expressed as a sum over “atomic” densities or densities localized at atomic sites. The atomic densities are determined self-consistently from a variational treatment of the total energy, which includes terms to account for kinetic energy due to the overlapping densities from separate a...

A. Shakibfar Sh. Ghammamy,

A new mixed  halo chromate  nanoparticle compound was synthesised and characterized. Triphenylphosphonium trifluoroiodochromate (III)[P(C6H5)3H]+[CrF3I]- nanoparticle was synthesized by using triphenylphosphonium  iodide reaction with CrF3, in the presence of  3-mercaptopropionic acid. This method is a simple and direc...

Journal: :SIAM J. Scientific Computing 2015
Michael Ulbrich Zaiwen Wen Chao Yang Dennis Klöckner Zhaosong Lu

The ensemble density functional theory is valuable for simulations of metallic systems due to the absence of a gap in the spectrum of the Hamiltonian matrices. Although the widely used self-consistent field iteration method can be extended to solve the minimization of the total energy functional with respect to orthogonality constraints, there is no theoretical guarantee on the convergence of t...

Journal: :iranian journal of science and technology (sciences) 2015
s. m. habibi-khorassani

inhibitory effect of three benzothiazole derivatives (1, 3-benzothiazol-2-amine (bta), 6-methyl-1, 3-benzothiazol-2-amine (mbta) and 2-amino-1, 3-benzothiazole-6-thiol (tbta)) on corrosion of carbon steel has been studied using density functional theory (dft) method in gas and aqueous phases. quantum chemical parameters such as ehomo (highest occupied molecular orbital energy), elumo (lowest un...

R. Ghahremani Gavineh Roudi S. Kazem Zadeh Anari Sh. Ghamami

That particles are of less than 100nm in diameter called nano particles (NPS) and there are in the world naturally like volcanic activity. In the present investigation a new mixed halomercurate nano particle compound was synthesised and characterized. Triphenylphosphonium trichloromercorate (II) [P(C6H5)3H]+[HgCl3]- nanoparticle was synthesi -zed by using triphenylphosphonium chloride reaction ...

2017
Ivana Adamovic Mark Alan Freitag Mark S. Gordon Mark A. Freitag

The effective fragment potential (EFP) method, is a discrete method for the treatment of solvent effects, originally formulated using Hartree–Fock (HF) theory. Here, a density functional theory(DFT) based implementation of the EFP method is presented for water as a solvent. In developing the DFT based EFP method for water, all molecular properties (multipole moments, polarizabilitytensors, scre...

2015

Density functional theory in Firefly is implemented for restricted, unrestricted, and restricted-open wavefunctions. For each wavefunction, energies and analytical gradients are available. Analytical Hessians are currently not available. Instead, Hessians can be calculated in a semi-numerical fashion. Double hybrid functionals are an exception – for these functionals, only energies are currentl...

Journal: :Journal of computational chemistry 2008
Ying Zhang Xin Xu Yijing Yan

We perform a systematic examination on the dependence of the calculated nuclear magnetic shielding constants on the chosen geometry for a selective set of density functional methods of B3LYP, PBE0, and OPBE. We find that the OPBE exchange-correlation functional performs remarkably well when either the optimized geometries or the experimental geometries are used. The popular B3LYP and PBE0 funct...

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