Reconstruction of signals or images from a few discrete Fourier transform (DFT) values has applications in MRI and SAR. Many real-world signals can be sparsified by an invertible transformation, such as wavelets, into a sparse (mostly zero, with K nonzero values at unknown locations) signal. This Ksparse signal can be reconstructed using the K lowestfrequency DFT values using Prony’s method or ...

We compare the performance of four recently developed DFT methods (MPW1B95, MPWB1K, PW6B95, and PWB6K) and two previous, generally successful DFT methods (B3LYP and B97-1) for the calculation of stacking interactions in six nucleic acid bases complexes and five amino acid pairs and for the calculation of hydrogen bonding interactions in two Watson– Crick type base pairs. We found that the four ...

All-electron path integral Monte Carlo (PIMC) and density functional theory molecular dynamics (DFT-MD) allow for a consistent first-principles investigation of hot, dense neon plasmas in the density-temperature range of 1–15 g cm−3 and 10–10 K. DFT-MD data at low temperatures combined with PIMC data at higher temperatures provides a coherent equation of state with a region of overlap in which ...

We present a first-principles computational study of solid 4He at T = 0 K and pressures up to ∼160 GPa. Our computational strategy consists in using van der Waals density functional theory (DFT-vdW) to describe the electronic degrees of freedom in this material, and the diffusion Monte Carlo (DMC) method to solve the Schrödinger equation describing the behavior of the quantum nuclei. For this, ...

The (13)C and (1)H isotropic chemical shift values computed at HF, BLYP, B3LYP, and MPW1PW91/6-311+G(2d,p) levels of theory, for the BLYP and B3LYP/6-31G(d,p) optimized geometries of adamantane, 2-adamantanone, and 2,4-methano-2,4-dehydroadamantane ([3.1.1] propellane) are reported and compared with the experimental data. Except for the "inverted" carbon atoms and some of their nearest neighbor...

The hyperpolarizabilities of five prototypical and four recently synthesized long-range charge-transfer (CT) organic compounds are calculated using short- and middle-range (SR and MR) hybrid functionals. These results are compared with data from MP2 and other DFT methods including GGAs, global hybrids, long-range corrected functionals (LC-DFT), and optimally tuned LC-DFT. Although it is commonl...

In this study the molecular geometries, experimental vibrational and electronic absorption spectra and quantum chemical calculations of free dimethyl phenylphosphonite, (C8H11PO2), (with synonym, dimethoxyphenylphosphine or phenyldimethoxyphosphine) (Abbreviated as DMPP) and its [Cd(DMPP)].Cl2.H2O metal halide complex have been investigated by using elemental analysis, FT-IR, micro-Raman and UV...

First-principles density functional theory (DFT) is used to study the solid-state modifications of carbon dioxide up to pressures of 60 GPa. All known molecular CO2 structures are investigated in this pressure range, as well as three non-molecular modifications. To account for long-range van der Waals interactions, the dispersion corrected DFT method developed by Grimme and co-workers (DFT-D3) ...

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...

The aim of this study was to assess the prevalence of dental caries and oral health practice of school children of 5-15 years of Bhaktapur, Nepal. Methods: Three hundred and forty school children were examined for decayed, missing and filled teeth. Decayed, Missing and Filled Teeth (DMFT) in permanent teeth and decayed and filled teeth (dft) in primary teeth were calculated. Then the DMFT index...