We present a critical analysis of the popular fragment-orbital density-functional theory (FO-DFT) scheme for the calculation of electronic coupling values. We discuss the characteristics of different possible formulations or "flavors" of the scheme which differ by the number of electrons in the calculation of the fragments and the construction of the Hamiltonian. In addition to two previously d...

Density functional theory (DFT) methods for calculating the quantum mechanical ground states of condensed matter systems are now a common and significant component of materials research. The growing importance of DFT reflects the development of sufficiently accurate functionals, efficient algorithms and continuing improvements in computing capabilities. As the materials problems to which DFT is...

Motivated by our recent investigation of spin–orbit mixing in the simplest singlet carbene, HCF, we report Density Functional Theory (DFT) calculations of the isotropic and anisotropic hyperfine coupling constants (HFCCs) of HCF ð ~ a3A00 Þ and other important triplet carbenes and biradicals. We conducted extensive DFT calculations on the prototypical triplet carbene, CH2, and compare our resul...

The excellent results of dispersion-corrected density functional theory (DFT-D) calculations for static systems have been well established over the past decade. The introduction of dynamics into DFT-D calculations is a target, especially for the field of molecular NMR crystallography. Four (13) C ss-NMR calibration compounds are investigated by single-crystal X-ray diffraction, molecular dynami...

This article starts with a brief history and idea interpretation of the Density Functional Theory (DFT), and then explains more detailedly about the original thought of Hohenberg and Kohn and their first and second theorem of the DFT. Next, it also introduces a methodology to treat the calculation based on DFT, which is the Kohn-Sham method based on the Local Density Approximation (LDA) treatme...

BACKGROUND Novel six organic donor-π-acceptor molecules (D-π-A) used for Bulk Heterojunction organic solar cells (BHJ), based on thienopyrazine were studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, to shed light on how the π-conjugation order influence the performance of the solar cells. The electron acceptor group was 2-cyanoacrylic for all compounds, wher...

We discuss the application of graphical processing units (GPUs) to accelerate real-space density functional theory (DFT) calculations. To make our implementation efficient, we have developed a scheme to expose the data parallelism available in the DFT approach; this is applied to the different procedures required for a real-space DFT calculation. We present results for current-generation GPUs f...

BACKGROUND Real-time spectral analyzers can be difficult to implement for PC computer-based systems because of the potential for high computational cost, and algorithm complexity. In this work a new spectral estimator (NSE) is developed for real-time analysis, and compared with the discrete Fourier transform (DFT). METHOD Clinical data in the form of 216 fractionated atrial electrogram sequen...

This paper presents the simulation of 4 Quadrature Amplitude Modulation (QAM) orthogonal frequency division multiplexing (OFDM) baseband system and channel estimation which uses inverse discrete Hartley transform (IDHT) and discrete Hartley transform (DHT). As the calculation of DHT and IDHT involves real operations hence the computational complexities are less as compared to DFT and IDFT. More...

The modern computer simulations of potential green solvents of the future, involving the room temperature ionic liquids, heavily rely on density functional theory (DFT). In order to verify the appropriateness of the common DFT methods, we have investigated the effect of the self-interaction error (SIE) on the results of DFT calculations for 24 ionic pairs and 48 ionic associates. The magnitude ...