Two methods of calculation of the 2-D DFT are analyzed.  The q2r×q2r-point 2-D DFT can be calculated by the traditional columnrow method with 2(q2r) 1-D DFTs, and we also propose the fast algorithm which splits each 1-D DFT by the short transforms by means of the fast paired transforms.  The q2r×q2r-point 2-D DFT can be calculated by the tensor or paired representations of the image, when the...

In this work, we studied a copper complex-based dye, which is proposed for potential photovoltaic applications and is named Cu (I) biquinoline dye. Results of electron affinities and ionization potentials have been used for the correlation between different levels of calculation used in this study, which are based on The Density Functional Theory (DFT) and time-dependent (TD) DFT. Further, the ...

Nowadays the state of the art Density Functional Theory (DFT) codes are based on local (LDA) or semilocal (GGA) energy functionals. Recently the theory of a truly nonlocal energy functional has been developed. It has been used mostly as a post DFT calculation approach, i.e. by applying the functional on the charge density calculated using any standard DFT code, thus obtaining a new improved val...

An efficient method of transforming a discrete Fourier transform (DFT) into a constant Q transform, where Q is the ratio of center frequency to bandwidth, has been devised. This method involves the calculation of kernels that are then applied to each subsequent DFT. Only a few multiples are involved in the calculation of each component of the constant Q transform, so this transformation adds a ...

For the first time, a complete implementation of coupled perturbed density functional theory ~CPDFT! for the calculation of NMR spin–spin coupling constants ~SSCCs! with pure and hybrid DFT is presented. By applying this method to several hydrides, hydrocarbons, and molecules with multiple bonds, the performance of DFT for the calculation of SSCCs is analyzed in dependence of the XC functional ...

This paper will look at an approach that uses symmetric properties of the basis function to remove redundancies in the calculation of discrete Fourier transform (DFT). We will develop an algorithm, called the quick Fourier transform (QFT), that will reduce the number of oating point operations necessary to compute the DFT by a factor of two or four over direct methods or Goertzel's method for p...

This paper looks at an approach that uses symmetric properties of the basis function to remove redundancies in the calculation of the discrete Fourier transform (DFT). We develop an algorithm, called the quick Fourier transform (QFT), that reduces the number of oating point operations necessary to compute the DFT by a factor of two or four over direct methods or Goertzel's method for prime leng...

FFT algorithms is one of the many methods used for the calculation of DFT, but they are preferred due to their increased speed and higher efficiency, which arises due to the fact that for the calculation of a N-point DFT, the sequence is broken into several segments and the DFT for each segment is calculated. However, for this many redundant memory spaces are required. The Butterfly structure f...

in this paper, the structural properties of the b30n20 molecule have been investigated at b3lyp/6-31g (d) level of theory. the optimized structure and electronic properties calculations for the studiedmolecule have been performed using gaussian 03 program. a mathematical equation of third degreewas exploited for the correlation and exchange energy with the number of primitives. the naturalbondi...