نتایج جستجو برای: calculations

تعداد نتایج: 111826  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده علوم پایه 1391

one of the applications of nanotechnology is use of carbon nanotubes for the targeted delivery of drug molecules. to demonstrate the physical and chemical properties of biomolecules and identify new material of drug properties, the interaction of carbon nanotubes (cnts) with biomolecules is a subject of many investigations. cnts is a synthetic compound with extraordinary mechanical, thermal, el...

Journal: :journal of physical & theoretical chemistry 2013
farideh keshavarz rezaei

the thermodynamic functions such as enthalpy (h), gibbs free energy (g) and entropy (s) ofpyrazole was theoretically studied at 5 different temperatures 25, 30, 35, 40 and 45°c by usinggussian o3, software. first, the structural optimization of isolated pyrazole was done in the gas phaseby appling the density functional theory (b3lyp) level with 3-21g, 6-31g and 6-31+g(d) basissets. moreover, v...

Journal: :journal of physical & theoretical chemistry 2011
m. kia v. pourghasem f. niksolat

in this work, theoretical investigations on carbon nanotube with oxygen atom have been carried out by firstprinciplescalculations and density functional theory and hartree fock theory in 3-216 and 6-316 basis sets. theinteraction energy of the oxygen atom to a cnt is calculated. the effects of this substitutions have beeninvestigated on the during transplantation (10,0) single-walled carbon nan...

پایان نامه :0 1392

nowadays in trade and economic issues, prediction is proposed as the most important branch of science. existence of effective variables, caused various sectors of the economic and business executives to prefer having mechanisms which can be used in their decisions. in recent years, several advances have led to various challenges in the science of forecasting. economical managers in various fi...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد شاهرود - دانشکده علوم پایه 1390

در این تحقیق ? کنفورماسیون های دی پپتیدhco–l-ser-l-ala–nh2و hco–d-ser-d-ala–nh2که در پروتئین های متعددی وجود دارد ? در فاز گازی مورد بررسی قرار گرفته است. محاسبات با استفاده از برنامه گوسین 3 و با بهره گیری از سطح تئوری g*31-6b3lyp/انجام شده است. بدین صورت که ابتدا ساختارهای بهینه و انرژی برای کنفورماسیون های حاصل از چرخش زاویه (c) به فواصل30 درجه از صفر درجه تا 360 درجه محاسبه شدند که سه مین...

Journal: :physical chemistry research 2013
hossein roohi e. ahmadepour

the structural and energetic characteristics of o3–h2o complexes have been investigated by means of b3lyp, mp2, mp4(sdtq), ccsd(t) and qcisd(t) methods in conjunction with the aug-cc-pvdz and aug-cc-pvtz basis sets. six conformers were found for the o3–h2o complex. two different intermolecular interactions were expected to participate in the formation of complexes, namely conventional o∙∙∙h hyd...

Journal: :physical chemistry research 2014
behzad chahkandi mohammad chahkandi bentolhoda ashrafi

an ab initio and density functional theory (dft) study about conformational analysis of tripeptide model hco−gly−l−ile−gly−nh2 is presented. the tripeptide was scanned about initial, central, and final residues, separately while for every scanning procedure the two other residues had been kept in the β conformation and side chain (sc) dihedral angles were maintained on the gauche− (g‾) state (χ...

Journal: :journal of physical & theoretical chemistry 2015
issa yavari hassan kabiri-fard

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g*for total energy calculation are reported for z-cyclooctene (1). the most favorable conformation of 1 is theunsymmetric boat-chair (1-bc) geometry. potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. the process via a chair transition sta...

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