The symmetry and periodicity properties of the discrete Fourier transform (DFT) allow a variety of useful and interesting decompositions. In particular, by clever grouping and reordering of the complex exponential multiplications it is possible to achieve substantial computational savings while still obtaining the exact DFT solution (no approximation required). Many “fast” algorithms have been ...

The optical computing technology ooers new challenges to the algorithm designers since it can perform an n-point DFT computation in only unit time. Note that DFT is a non-trivial computation in the PRAM model. We develop two new models, DFT-VLSIO and DFT-Circuit, to capture this characteristic of optical computing. We also provide two paradigms for developing parallel algorithms in these models...

The DFT based OFDM (DFT-OFDM) has currently drawn most of attention in the area of wireless communication. But, there is a long way to go to pursue higher bandwidth efficiency. Discrete wavelet transform has been proposed to substitute DFT, due to its higher spectral containment between subchannels, which can eliminate cyclic prefix (CP) that a must in DFT-OFDM system. In this paper, we propose...

A recently proposed "DFT + dispersion" treatment (Rajchel et al., Phys. Rev. Lett., 2010, 104, 163001) is described in detail and illustrated by more examples. The formalism derives the dispersion-free density functional theory (DFT) interaction energy and combines it with the dispersion energy from separate DFT calculations. It consists of the self-consistent polarization of DFT monomers restr...

BACKGROUND Recent results from the largest multicenter randomized trial (Shockless IMPLant Evaluation [SIMPLE]) on defibrillation threshold (DFT) testing suggest that while shock testing seems safe, it does not reduce the risk of failed shocks or prolong survival. A contemporary systematic review of DFT versus no-DFT testing at the time of implantable cardioverter-defibrillator implantation was...

BACKGROUND Identification of individual factors associated with high defibrillation threshold (DFT) seems to be of high clinical importance. Impedance cardiography (ICG) may be used for non-invasive evaluation of the haemodynamic status. Whether ICG parameters may improve identification of patients with high DFT has not yet been examined. AIM To evaluate clinical risk factors of high DFT incl...

A key quantity for molecule-metal interfaces is the energy level alignment of molecular electronic states with the metallic Fermi level. We develop and apply an efficient theoretical method, based on density functional theory (DFT) that can yield quantitatively accurate energy level alignment information for physisorbed metal-molecule interfaces. The method builds on the "DFT+Σ" approach, groun...

The use of density functional theory (DFT) and time-dependent DFT (TD-DFT) to study the photochemistry of metal complexes is becoming increasingly important among chemists. Computational methods provide unique information on the electronic nature of excited states and their atomic structure, integrating spectroscopy observations on transient species and excited-state dynamics. In this contribut...

Density functional theory (DFT) has provided many insights into the freezing of simple fluids. Several analytical and numerical solution have shown that the DFT provides an accurate description of freezing of hard spheres and their mixtures. Compared to other techniques, numerical, grid-based algorithms for solving the DFT equations have more variational freedom and are capable of describing su...