相关论文: Study of distortion effects and clustering of isot…
A Shadow Wave Function (SWF) is employed along with Variational Monte Carlo techniques to describe the ground state properties of solid molecular para-hydrogen. The study has been extended to densities below the equilibrium value, to obtain…
We study molecular para-hydrogen (p-${\rm H_{2}}$) and ortho-deuterium (o-${\rm D_{2}}$) in two dimensions and in the limit of zero temperature by means of the diffusion Monte Carlo method. We report energetic and structural properties of…
It is shown by computer simulations that superfluid {\it para}-hydrogen clusters of more than 22 molecules can be turned insulating and "solidlike" by the replacement of as few as one or two molecules, with ones of the heavier {\it…
The quantum diffusion of ortho-H2 impurities in solid para-H2 has been investigated with a torsional oscillator technique. The unclustering dynamics of agglomerated impurities with increasing temperature are found to greatly affect the…
The electronic and optical properties of single-layer (SL) tungsten disulfide (WS$_2$) in the presence of substitutional Holmium impurities (Ho$_{\rm W}$) are studied. Although Ho is much larger than W, density functional theory (DFT)…
We report laboratory measurements of the absorption coefficient of solid para-H2, within the wavelength range from 1 to 16.7 micron, at high spectral resolution. In addition to the narrow rovibrational lines of H2 which are familiar from…
We have detected new HD absorption systems at high redshifts, z_abs=2.626 and z_abs=1.777, identified in the spectra of the quasars J0812+3208 and Q1331+170, respectively. Each of these systems consists of two subsystems. The HD column…
We have determined the ground-state energies of para-H$_2$ clusters at zero temperature using the diffusion Monte Carlo method. The liquid or solid character of each cluster is investigated by restricting the phase through the use of proper…
We use density functional methods to identify the atomic configurations of H and D atoms trapped by O impurities and embedded in bulk Nb. We calculate the double-well potential for O-H and O-D impurities, wave functions, and tunnel…
In the fcc lattice of Pd, hydrogen occupies octahedral interstitial positions with cubic symmetry. One could therefore expect that in dilute solid H solutions in Pd the fundamental band of optical H vibrations should be reduced to a narrow…
We present a machine learning algorithm for the prediction of molecule properties inspired by ideas from density functional theory. Using Gaussian-type orbital functions, we create surrogate electronic densities of the molecule from which…
The transport of heavy, neutral or charged, point-like particles by incompressible, resistive magnetohydrodynamic (MHD) turbulence is investigated by means of high-resolution numerical simulations. The spatial distribution of such…
We report a quantitative experimental study of the crystallization kinetics of supercooled quantum liquid mixtures of para-hydrogen (pH$_2$) and ortho-deuterium (oD$_2$) by high spatial resolution Raman spectroscopy of liquid microjets. We…
Defects in crystalline silicon consisting of a silicon self-interstitial atom and one, two, three, or four hydrogen atoms are studied within density-functional theory (DFT). We search for low-energy defects by starting from an ensemble of…
Clusters of para-hydrogen (pH2) have been predicted to exhibit superfluid behavior, but direct observation of this phenomenon has been elusive. Combining experiments and theoretical simulations, we have determined the size evolution of the…
We use coupled-cluster quantum chemical methods to calculate the energetics of molecular clusters cut out of periodic molecular hydrogen structures that model observed phases of solid hydrogen. The hydrogen structures are obtained from…
The possibility that disorder may stabilize a superfluid phase of para-hydrogen in two dimensions is investigated theoretically by means of Quantum Monte Carlo simulations. We model disorder using a random distribution of scatterers, and…
We theoretically investigate the ground-state properties of a molecular para-hydrogen (p-H2) film in which crystallization is energetically frustrated by embedding sodium (Na) atoms periodically distributed in a triangular lattice. In order…
Hydrogen segregation to vacancies in the surface and subsurface layers of (111) and (100) surfaces of Pd is studied in the density functional theory (DFT) approach. Adsorption energies and configurations of various clusters of H atoms at…
CeO$_2$ (ceria) is an attractive material for heterogeneous catalysis applications involving hydrogen due to its favorable redox activity combined with its relative impermeability to hydrogen ions and molecules. However, to date, many bulk…