نتایج جستجو برای: oniom and dft
تعداد نتایج: 16829513 فیلتر نتایج به سال:
In this study, the effect of the secondary structure of the protein on the acid strength of three structures of random (R), alpha helix (α) and beta sheet (b) were investigated theoretically. These structures are related to the cationic amino acids of histidine and lysine in the polypeptide chain of eight-glycine residue. Computational methods at the HF, B3LYP, X3LYP and M05-2X levels in t...
in this research we have studied the effect of some transition-metals (cu, ag and au) substitutions on two-electron reduction potential of flavins by application of dft method. all geometries have been optimized at blyp level of theory and “6-31+g** + lanl2dz” mixed basis set. the frequency job at the same method and basis sets has been performed to obtain gibbs free energy of compounds. it h...
Linear–dendrite copolymers containing hyper branched poly(citric acid) and linear poly(ethylene glycol) blocks PCA–PEG–PCA are promising nonmaterial to use in nanomedicine. To investigate their potential application in biological systems (especially for drug carries) ONIOM2 calculations were applied to study the nature of particular interactions between drug and the polymeric nanoparticle...
in this research, the interactions of hcn gas with pristine, ga-, n- and gan-doped of boron phosphide nanotube (bpnts) were investigated by using density function theory (dft). the structure, electrical and nqr parameters, quantum descriptors involving energy gap, global hardness, global softness, electrophilicity, electronic chemical potential and electronegativity were calculated. the adsorpt...
The implementation of OFDM transmitters typically consists of a discrete DFT matrix and a digital-to-analog (DAC) converter. Many existing results on the analysis of OFDM systems, e.g., spectral roll-off, are based on a convenient analog representation. In this paper, we show that the analog representation and the DFT-based OFDM transmitters are equivalent only in special cases. Using the analo...
In this study, functionalized β-cyclodextrin (β-CD) by aldehyde group was investigated as an oxidase enzyme mimic for the amino phenol oxidation. All calculations were performed by GAUSSIAN 09 package using two layers ONIOM method at the ONIOM (MPW1PW91/6-311++G(d,p)/UFF) level. In the first step, H2O2 is encapsulated in the hydrophobic cavity. In the second step, H2<...
The geometrical frustration in the magnetic pyrochlore oxides causes interesting properties at low temperatures in these materials. Therefore, we studied two challenging materials, Er2Ti2O7 and Tb2Ti2O7, using an ab intio method, based on Density Functional Theory (DFT). To take into account the f electrons coulomb interactions correctly, we employed DFT+U, a Hubbard method correction. As spin-...
Different deprotonation paths of the radical cation formed by one-electron oxidation of 2'-deoxyguanosine (2dG) sites in DNA have been studied using Density Functional Theory (M05-2X/6-31+G(d,p)) and ONIOM methodology (M05-2X/6-31+G(d,p):PM6) in conjunction with the SMD model to include the solvent effects. Models of increased complexity have been used ranging from the isolated nucleoside to a ...
Hybrid QM:QM (quantum mechanics:quantum mechanics) and QM:MM (quantum mechanics:molecular mechanics) methods are widely used to calculate the electronic structure of large systems where a full quantum mechanical treatment at a desired high level of theory is computationally prohibitive. The ONIOM (our own N-layer integrated molecular orbital molecular mechanics) approximation is one of the more...
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