نتایج جستجو برای: ab initio method

تعداد نتایج: 1666872  

2017
Fuyang Tian

Similar to the importance of XRD in experiments, ab initio calculations, as a powerful tool, have been applied to predict the new potential materials and investigate the intrinsic properties of materials in theory. As a typical solid-solution material, the large degree of uncertainty of high-entropy alloys (HEAs) results in the difficulty of ab initio calculations application to HEAs. The prese...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه پیام نور 1386

چکیده ندارد.

Journal: :Journal of computational chemistry 2013
Christiane Regina Soares Brasil Alexandre C. B. Delbem Fernando Luís Barroso da Silva

This article focuses on the development of an approach for ab initio protein structure prediction (PSP) without using any earlier knowledge from similar protein structures, as fragment-based statistics or inference of secondary structures. Such an approach is called purely ab initio prediction. The article shows that well-designed multiobjective evolutionary algorithms can predict relevant prot...

Journal: :Pacific Symposium on Biocomputing. Pacific Symposium on Biocomputing 1996
R P Muller A Warshel

This paper describes a hybrid ab initio quantum mechanical/molecular mechanics (QM/MM) method for calculating activation free energies of chemical reactions in solution, using molecular mechanics force fields for the solvent and an ab initio technique that incorporates the potential from the solvent in its Hamiltonian for the solute. The empirical valence bond (EVB) method is used as a referenc...

Journal: :Proteins 2003
Yu Shao Christopher Bystroff

We present a novel method, HMMSTR-CM, for protein contact map predictions. Contact potentials were calculated by using HMMSTR, a hidden Markov model for local sequence structure correlations. Targets were aligned against protein templates using a Bayesian method, and contact maps were generated by using these alignments. Contact potentials then were used to evaluate these templates. An ab initi...

2009
J A Yasi

The core structures of screw and edge dislocations on the basal and prism planes in Mg, and the associated gamma surfaces, were studied using an ab initio method and the embedded-atom-method interatomic potentials developed by Sun et al and Liu et al. The ab initio calculations predict that the basal plane dislocations dissociate into partials split by 16.7 Å (edge) and 6.3 Å (screw), as compar...

2016
JIE FU

Ab initio calculation based on density function theory (DFT) is an accurate and efficient method for modelling material properties. It is performed by solving the Shrödinger equations with a few assumptions to obtain the physical properties of the system. It is very computational demanding when dealing with large systems or longtime simulations. Developing empirical potentials on the basis of a...

2005
J.Robert Huber

The state-selective photodissociation of methylnitrite CH30NO(So,v) + hv -+ CH30+ NO(t,r,v) is reviewed and the dynamics of the bond-breaking process is analysed in connection with an ab initio S1-potential energy surface of the parent molecule. Experimental and theoretical results reveal an interesting picture of the dissociation path of a polyatomic molecule which decays by vibrational predis...

Journal: :Journal of Computational Chemistry 2000
Yirong Mo Jiali Gao

and valence bond method, solvent effects on S N 2 reaction, and Monte Carlo simulations of chemical reaction in solution. Abstract: A mixed molecular orbital and valence bond (MOVB) method is described in combined ab initio QM/MM simulations of the S N 2 reaction of Cl-+ CH 3 Cl _ ClCH 3 + Cl-in water. The method is based on the construction of individual charge-localized, diabatic states using...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده علوم پایه 1390

این رساله شامل پنج فصل است. در فصل اول به مفاهیم مقدماتی و معرفی سایلیلن ها پرداخته ایم. با توجه به اینکه سایلیلن ها در شیمی حدواسط های فعال اهمیت به سزایی دارند، بررسی پایداری و خواص ساختاری آن ها از لحاظ آروماتیسیته، نوکلئوفیلیسیته و الکتروفیلیسیته در واکنش ها امری ضروری به نظر می رسد. در فصل دوم، پایداری n-هتروسیکل سایلیلن هایی مورد بررسی قرار گرفت که از سه ایزومر 2-، 3- و 4- سیلاپیریدین مشت...

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