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The WIEN2k program is based on the augmented plane wave plus local orbitals (APW+lo) method to solve the Kohn–Sham equations of density functional theory. The APW+lo method, which considers all electrons (core and valence) self-consistently in a full-potential treatment, is implemented very efficiently in WIEN2k, since various types of parallelization are available and many optimized numerical libraries can be used. Many properties can be calculated, ranging from the basic ones, such as the electronic band structure or the optimized atomic structure, to more specialized ones such as the nuclear magnetic resonance shielding tensor or the electric polarization. After a brief presentation of the APW+lo method, we review the usage, capabilities, and features of WIEN2k (version 19) in detail. The various options, properties, and available approximations for the exchange-correlation functional, as well as the external libraries or programs that can be used with WIEN2k, are mentioned. References to relevant applications and some examples are also given. [ABSTRACT FROM AUTHOR]

Author(s): Clemens J. Först [1, 2]; Christopher R. Ashman [1]; Karlheinz Schwarz [2]; Peter E. Blöchl (corresponding author) [1] The ability of the semiconductor industry to continue scaling microelectronic devices [...]

A study of the existence of non-nuclear maxima (NNM) in the electron density of simple metals is presented. The calculations are based on density functional theory and the linearized augmented plane wave method in which the basis set quality can be systematically improved. We find that only lithium and beryllium exhibit NNM at calculated and experimental equilibrium volumes. The existence of NNM is found to be caused by a relatively small extension of their core densities. The NNM appear in both the local density and generalized gradient approximations. The use of the latter favors the existence of NNM and at the same time improves the agreement with measured structure factors and lattice constants. Therefore, we argue that it is very likely that NNM would also appear for the exact functional. [ABSTRACT FROM AUTHOR]

The molecular structure and dynamics of beryllocene are investigated using the Car–Parrinello projector augmented wave method. In the ground state, the molecule prefers a η1–η5-coordinated conformation of CS symmetry. At finite temperature, beryllocene undergoes rapid hapticity changes with a frequency of 1–5×1012 s-1. This occurs by means of two mechanisms, each corresponding to a saddle point of the potential surface elevated 5 and 8 kJ mol-1 above the minimum, respectively. The saddle points have CS and C2h symmetry, respectively. The geometric and electronic structure at finite temperature are discussed. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A first-principles molecular dynamics calculation of ferrocene [Fe(C5H5)2] at 300 K, based on the local density approximation, is presented. Kohn–Sham equations and forces on the atoms are obtained using the projector augmented wave technique. Frequencies and eigenmodes are derived by fitting a system of harmonic oscillators to the molecular dynamics trajectory. Frequency shifts for deuterated ferrocene [Fe(C5D5)2, ferrocene-d10] and the corresponding eigenvectors are obtained by diagonalizing the dynamical matrix after renormalizing it according to the changed masses. Most experimental and theoretical frequencies agree to about 2.5% (or 20 wave numbers), with the exception of six modes for which a new assignment is proposed. [ABSTRACT FROM AUTHOR]

Abstract: Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the accuracy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate discussions around QCr, but not to find a final definition of the field. [ABSTRACT FROM AUTHOR]

The routinely made assumptions for simulating solid materials are briefly summarized, since they need to be critically assessed when new aspects become important, such as excited states, finite temperature, time-dependence, etc. The significantly higher computer power combined with improved experimental data open new areas for interdisciplinary research, for which new ideas and concepts are needed. [ABSTRACT FROM AUTHOR]

The site occupation of binary Fe-Cr, Co-Cr, Re-W and Fe-V sigma phases is studied in the present work with a first-principles-based single-site mean field theory. We show that the alloy components in these systems exhibit similar site preferences except for the Re-W system, where the occupation of two sites is reversed in agreement with previously published works. In case of the FeV sigma phase, for which the size mismatch between the alloy components is large, we also include into our consideration the effect of local lattice relaxations. The obtained results are found in good agreement with the experimental data and previous theoretical studies. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to power system automation, based on distributed intelligence rather than traditional centralized control. The paper investigates the interplay between two international standards, IEC 61850 and IEC 61499, and proposes a way of combining of the application functions of IEC 61850-compliant devices with IEC 61499-compliant “glue logic,” using the communication services of IEC 61850-7-2. The resulting ability to customize control and automation logic will greatly enhance the flexibility and adaptability of automation systems, speeding progress toward the realization of the smart grid concept. [ABSTRACT FROM PUBLISHER]

Aspects of the progress over the last 40-50 years in calculating the electronic structure of solids and surfaces are sketched in the context of collaboration on the code now called WIEN2k. Different facets that are relevant for material sciences are discussed, ranging from quantum mechanics to the augmented plane wave (APW) method, as well as improvements in computer hardware and algorithms and related numerical accuracy. In this long period, the complexity and realism of applications to condensed matter systems has significantly increased and many properties which are closely related to experiments can now be calculated. This progress is illustrated by the fact that WIEN2k now is used worldwide by more than 1600 groups. The major steps in this development are illustrated for a few selected examples. [ABSTRACT FROM AUTHOR]

The dynamics of carboxylate ligands on the surface of zirconium oxo clusters was investigated in two case studies. Zr4O2(methacrylate)12was investigated by one- and two dimensional NMR spectra both in the solid state and in solution. In solution, the cluster is C2hsymmetric; stepwise intramolecular exchange of the four non-equivalent ligands was observed when the temperature was raised from −80 °C to −50 °C. The individual exchange processes were assigned to different ligand positions. Ab initiomolecular dynamics simulations were performed for Zr6(OH)4O4(formate)12to study the trajectory for the rearrangement of three chelating ligands into bridging positions, i.e.the conversion of the C3-symmetric into an Oh-symmetric cluster. The observation of a dip in the energy barrier along the reaction coordinate was related to the intermediate formation of hydrogen bonds between the moving oxygen atom of the rearranging ligand and a μ3-OH group of the cluster. Thus, the motion of the ligand requires a concerted motion in three dimensions. [ABSTRACT FROM AUTHOR]

Gd endohedral complexes of C82 fullerenols were synthesized and mass spectrometry analysis of their composition was carried out. It was established that the synthesis yields a series of fullerenols Gd@C82Ox(OH)y (x = 0, 3; y = 8, 16, 24, 36, 44). The atomic and electronic structure and properties of the synthesized fullerenols were investigated using the density functional theory calculations. It was shown that the presence of endohedral gadolinium increases the reactivity of fullerenols. It is proposed that the high-spin endohedral fullerenols are promising candidates for application in magnetic resonance imaging. [ABSTRACT FROM AUTHOR]