in recent years there has been considerable interest in the structures, energies and thermodynamics of(gan)4 clusters and it is the subject of many experimental and theoretical studies because of theirfundamental importance in chemical and physical process. all calculation of this study is carried outby gaussian 98. geometry optimization for (gan)4 nanocluster are be fulfilled at b3lyp, b1lypan...

bcn compounds have been researched theoretically and experimentally widely. in this paper, weintroduce the theoretical prediction of ternary b-c-n compounds. nmr spectroscopy was employedextensively to study these ternary nanostructures. we discuss the utilization of chemical shiftinformation as well as ab initio calculations of nuclear shielding for h20134c9n4 structuredetermination. we calcul...

p53 is one of the gene that has important role in human cell cycle and in the human cancers too.models of codon substitution make it possible to separate mutational biases in the dna fromselective constraints on the protein, and offer a great advantage over amino acid models forunderstanding the evolutionary process of proteins and protein-coding dna sequences. in thiswork, we investigated abou...

interaction of meso — tetrakis (p-sulphonato phenyl) porphyrin (hereafter abbreviated to tspp)with na+ has been examined using hf level of theory with 6-31g* basis set. counterpoise (cp)correction has been used to show the extent of the basis set superposition error (bsse) on thepotential energy curves. the numbers of na+ have a significant effect on the calculated potentialenergy curve (includ...

Empirical tight binding has proven to be very popular in recent years on account of its computational efficiency and accuracy. However, it has limitations, notably the difficulties associated with fitting parameters and improving models when the desired accuracy cannot be achieved. In the light of this, a number of efforts have been made to derive tight-binding models from first principles. Her...

An ab-initio description of atomic nuclei that solves the nuclear many-body problem for realistic nuclear forces is expected to possess a high degree of predictive power. In this contribution we treat the main obstacle, namely the short-ranged repulsive and tensor correlations induced by the realistic nucleon-nucleon interaction , by means of a unitary correlation operator. This correlator appl...

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...

Ab initio structure prediction seeks to predict the native conformation of a protein from the amino acid sequence alone. Such attempts are both a fundamental test of our understanding of protein folding, and an important practical challenge in this era of large scale genome sequencing projects, which are producing large numbers of protein sequences for which no three-dimensional structural info...

NMR chemical shifts for an L-alanine molecular crystal are calculated using ab initio plane wave density functional theory. Dynamical effects including anharmonicity may be included by averaging chemical shifts over an ensemble of structural configurations generated using molecular dynamics (MD). The time scales required mean that ab initio MD is prohibitively expensive. Yet the sensitivity of ...

Low-energy nuclear theory has entered an era of ab initio nuclear structure and reaction calculations based on QCD. One of the most promising paths from QCD to nuclear observables employs Hamiltonians constructed within chiral effective field theory as starting point for precise ab initio studies. However, the full inclusion of chiral twoplus three-nucleon (NN+3N) interactions in exact and appr...