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Sparse matter is abundant and has both strong local bonds and weak nonbonding forces, in particular nonlocal van der Waals (vdW) forces between atoms separated by empty space. It encompasses a broad spectrum of systems, like soft matter, adsorption systems and biostructures. Density-functional theory (DFT), long since proven successful for dense matter,(More)
We propose a second version of the van der Waals density functional of Dion et al. ͓Phys. Rev. Lett. 92, 246401 ͑2004͔͒, employing a more accurate semilocal exchange functional and the use of a large-N asymptote gradient correction in determining the vdW kernel. The predicted binding energy, equilibrium separation, and potential-energy curve shape are close(More)
Molecular hydrogen adsorption in a nanoporous metal-organic framework structure (MOF-74) is studied via van der Waals density-functional calculations. The primary and secondary binding sites for H(2) are confirmed. The low-lying rotational and translational energy levels are calculated, based on the orientation and position dependent potential energy(More)
Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray(More)
The role of low binding energy sites on the adsorption of H(2) in metal-organic frameworks (MOFs) with unsaturated metal centers has not been identified. For instance, the importance of the benzene sites on H(2) adsorption at the metal site in MOF-74 has not been established. We report here experimental evidence that unambiguously shows that the internal(More)
The adsorption energies of small molecules in nanoporous materials are often determined by isotherm measurements. The nature of the interaction and the response of the host material, however, can best be studied by spectroscopic methods. We show here that infrared absorption and Raman spectroscopy measurements together with density functional theory(More)
Infrared (IR) absorption spectroscopy measurements of molecular hydrogen in MOF-74-M (M = metal center) are performed as a function of temperature and pressure [to 45 kTorr (60 bar) at 300 K, and at lower pressures in the 20-200 K range] to investigate the nature of H(2) interactions with the unsaturated metal centers. A small shift (∼ -30 cm(-1) with(More)
Bloodstain age is a parameter that can be used in crime scene investigations. Bloodstain age can be determined by measuring the 18S rRNA:β-actin mRNA ratio by Reverse Transcription-quantitative PCR (RT-qPCR). Since this ratio is a function of time, it can be used as an estimator of bloodstain age. However, it is important to validate the technique in a(More)
A microporous metal organic framework structure, Zn(2)(bpdc)(2)(bpee).2DMF (DMF: N,N-dimethylformamide), has been synthesized via solvothermal reactions. The compound is a new member of the RPM series (RPM = Rutgers Recyclable Porous Material) that possesses a flexible and recyclable three-dimensional framework containing one-dimensional channels. It(More)