New Cap-Holed AlP, GaP, and InP Nanotubes.

The structural, vibrational, and electronic properties of new inorganic X-phosphide nanotubes (-XPNT), with X = Al, Ga, or In and chirality of (5,5), are investigated. These new NTs display ends, with the features induced by the nonpassivated ends. Studies are based on density functional theory (DFT) using the M06-2X, PBE, and B3LYP functionals together with the LanL2DZ basis set.

Encapsulation of Pollutant Gaseous Molecules by Adsorption on Boron Nitride Nanotubes: A Quantum Chemistry Study.

Based on density functional theory (DFT) and the semiempirical method PM7, we analyze the encapsulation process of polluting gases and/or their adsorption on different sites, viz., on the inner wall, the outer wall, and on the boron nitride (BN) nanotube ends, with chirality (7,7) armchair. DFT calculations are performed using the Perdew-Burke-Ernzerhof (PBE) functional and the M06-2X method through the 6-31G(d) divided valence orbitals as an atomic basis.

Comparing two high correlation models to test the mechanical stability of americium-II.

In this work two high density functional theory (DFT) correlation methodologies, the so called DFT+U (or GGA+U) implementation and the exact exchange of correlated electrons (EECE), hybrid DFT functional (or one case of hybrid DFT), are tested to determine the mechanical properties of americium-II. For each case, the numeric value of their principal parameter is chosen ([Formula: see text] for the first case and [Formula: see text] for the second one) once the crystalline structure meets all the mechanical stability conditions. The results show that there is a range of values of [Formula: see text] and [Formula: see text] in which both methodologies generate a stable (experimentally correct) non-magnetic ground state, reaching approximately the same numeric value of the set of elastic constants of the cubic structure.

Confined helium atom low-lying S states analyzed through correlated Hylleraas wave functions and the Kohn-Sham model.

Calculation including the electron correlation effects is reported for the ground 1 1S and lowest triplet 1 3S state energies of the confined helium atom placed at the center of an impenetrable spherical box. While the adopted wave-functional treatment involves optimization of three nonlinear parameters and 10, 20, and 40 linear coefficients contained in wave functions expressed in a generalized Hylleraas basis set that explicitly incorporates the interelectronic distance r12, via a Slater-type exponent and through polynomial terms entering the expansion, the Kohn-Sham model employed here uses the Perdew and Wang exchange-correlation functional in its spin-polarized version within the local-density approximation (LDA) with and without the self-interaction correction. All these calculations predict a systematic increase in the singlet-triplet energy splitting toward the high confinement regime, i.