We present a theoretical investigation of the hydrogenation of pyrene and of the subsequent molecular hydrogen evolution. Using density functional theory (DFT) at the GGA-PBE level, the chemical binding of atomic hydrogen to pyrene is found to be exothermic by up to 1.6 eV with a strong site dependence. The edge C atoms are found most reactive. The barrier for the formation of the hydrogen-pyre...

Deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals play a crucial role in modern laser frequency conversion technology. Traditionally, the exploration of deep-UV NLO crystals is mainly focused on borates, while, the use of phosphates recently opened up a novel and promising non-boron pathway for designing new deep-UV NLO crystals. Extending this pathway to aluminosilicates led to the d...

There is a compelling reason to design cost-effective sensors detect and measure harmful molecules such as dichlorosilane (H 2 SiCl ) in the air. In this work, density functional theory (DFT) has been used study nature of intermolecular interactions between H gas molecule with single-walled pristine, Al-doped, Ga-doped boron nitride nanotubes (BNNT, BNAlNT, BNGaNT, respectively) investigate the...

Conjugated copolymers with an alternating donor-acceptor (D-A) architecture are exploited as low-bandgap and high-hole-mobility materials in organic electronics. However, several of the presently available modeling methods predict different geometries and electronic properties for the same copolymer. In this work, the effect of the amount of exact Hartree-Fock (HF) exchange in density functiona...

Since the discovery of their excellent performance as the light-absorbing semiconducting component in photovoltaic cells, the PbX3CH3NH3 (X = I, Br, Cl) perovskites have received renewed attention. The five polymorphs stable above 200 K - the tetragonal phases for X = I, Br, Cl and the cubic phases for X = I, Br - were studied using periodic DFT calculations involving hybrid functionals (PBE0 a...

Hybrid Fock exchange/density functional theory functionals have shown to be very successful in describing a wide range of molecular properties. For periodic systems, however, the long-range nature of the Fock exchange interaction and the resultant large computational requirements present a major drawback. This is especially true for metallic systems, which require a dense Brillouin zone samplin...

A recently developed MESS-E-QM/MM method (multiple-environment single-system quantum mechanical molecular/mechanical calculations with a Roothaan-step extrapolation) is applied to the computation of hydration free energies for the blind SAMPL4 test set and for 12 small molecules. First, free energy simulations are performed with a classical molecular mechanics force field using fixed-geometry s...

In the present study, the performance of six popular density functionals (B3LYP, PBE0, BLYP, BP86, PBE, and SVWN) for the description of the autoionization process in the water octamer was studied. As a benchmark, MP2 energies with complete basis sets limit extrapolation and CCSD(T) correction were used. At this level, the autoionized structure lies 28.5 kcal.mol(-1) above the neutral water oct...

The interaction of Au(n) and Pt(n) (n=2,3) clusters with the stoichiometric and partially reduced rutile TiO(2) (110) surfaces has been investigated using periodic slab and periodic electrostatic embedded cluster models. Compared to Au clusters, Pt clusters interact strongly with both stoichiometric and reduced TiO(2) (110) surfaces and are able to enhance the reducibility of the TiO(2) (110) s...

The geometry of tetracyanoplatinate(II) (TCP) has been optimized with density functional theory (DFT) calculations in order to compare different computational strategies. Two approximate scalar relativistic methods, i.e. the scalar zeroth-order regular approximation (ZORA) and non-relativistic calculations with relativistic effective core potentials (ECPs), were benchmarked against the four-com...