Medea Vasp

Electronic structure calculations have become a powerful foundation for computational materials engineering. Four major factors have enabled this unprecedented evolution, namely (i) the development of density functional theory (DFT), (ii) the creation of highly efficient computer programs to solve the Kohn-Sham equations, (iii) the integration of these programs into productivity-oriented computational environments, and (iv) the phenomenal increase of computing power.

In this context, we describe recent applications of the Vienna Ab-initio Simulation Package (VASP) within the MedeA ® computational environment, which provides interoperability with a comprehensive range of modeling and simulation tools. The focus is on technological applications including microelectronic materials, Li-ion batteries, high-performance ceramics, silicon carbide, and Zr alloys for nuclear power generation.

Learn how high throughput calculations in MedeA make simulations straightforward. Upcoming #Webinar: #VASP in MedeA: A Fast Way- From Models to.

A discussion of current trends including high-throughput calculations concludes this article. IntroductionMore than ever before, our society depends on a perplexing multitude of materials to meet needs such as housing, heating/cooling, clean water, production of food, energy, infrastructure, communication, transportation, and health care, as well as allowing recreational and artistic activities. It is fair to say that until now the materials necessary for all these purposes have been developed by experimental methods. Although the fundamental physical and chemical laws that govern the properties of materials are known, the goal of designing materials with specific properties by a purely theoretical/computational approach remains elusive. The role of atomistic simulations within an integrated computational materials engineering approach.In the following sections, recent applications will be presented, which demonstrate current capabilities of predicting materials properties from ab initio computations as part of materials engineering. These applications include published as well as unpublished work. In all cases the Vienna Ab-initio Simulation Package (VASP)– within the MedeA ® software environment with its various tools has been used.

2.1 The TiN/HfO 2 interface in high-k dielectricsIn complementary metal oxide semiconductor (CMOS) technology, steadily diminishing device sizes have mandated the introduction of high-k dielectrics such as hafnium dioxide, which are replacing pure silicon dioxide dielectric layers. As a consequence, to maintain a low threshold voltage for switching, the material for the gate metal has had to be changed. Titanium nitride has emerged as a suitable choice in this role. A key requirement for energy efficient switching of CMOS devices is the alignment of the Fermi level ( i.e. The energy of the highest occupied states) of the metallic gate with the band edges of the semiconducting channel of the device, as illustrated in.

In the event that you are working with the moderate framework, at that point, you need to download it and introduce it to lift up the framework on the grounds that download cleans the slam and makes your PC quicker, and your gadget will likewise be capable for performing various tasks.It also emphasizes all the types of security and privacy issues that you mostly bother about nowadays. Before fixing all types of PC issues Auslogics BoostSpeed 11.4.0.3 Torrent, first of all, perform a complete check-up of your OS and only fix the issues and does not take the unnecessary time-consuming actions because the correct diagnosis is the key to success of any procedure.As like every single working framework bolster it and it is completely perfect with most recent discharged Windows 10. The powerful Auslogics BoostSpeed 2020 Patch with Activation Key has the ability to perform its functions automatically when needed without disturbing you once you install it in your PC and automatically guard you against any types of threats. In short, you can get the world’s best system protection and management benefits by using this splendid tool. Crack boostspeed 5.1.1.0.

Left panel: schematic diagram of the energy levels across a stack of semiconducting Si (the channel of the transistor), the gate oxide consisting of SiO 2 and HfO 2, and the TiN gate metal. To achieve optimal energy consumption of a p-doped CMOS, the Fermi level of the metal has to be aligned with the top of the valence band of the semiconductor. This is achieved by increasing the work function of TiN. Right panels: (a) atomistic model of HfO 2/TiN interface with some N replaced by O; (b) O atoms are replaced by N atoms only at the HfO 2/TiN interface. Panels (c) and (d) show the change of the work function due to the chemical changes in the system.Empirically it was found that annealing of the as-deposited TiN in an oxygen atmosphere increased the work function, as desired. Secondary ion mass spectroscopy (SIMS) measurements showed that oxygen atoms had penetrated into the layer of TiN. It was thus concluded that the replacement of oxygen in TiN causes the increase of the work function.

Using MedeA ®-VASP, detailed electronic structure calculations of models of the HfO 2/TiN interface revealed, however, that replacement of N by O inside the TiN layer did not change the work function ( cf. One could have concluded that computed results and experiment are in contradiction. Actually, this is not the case. While annealing of the stack in an oxygen-containing atmosphere leads to ingress of oxygen into the TiN layer, the O atoms inside the TiN layer are not the cause for the work function increase. Rather, calculations revealed that, driven by the ingress of O atoms, the diffusion of N atoms, and the filling of O vacancies in the HfO 2 layer, the replacement of O atoms by N atoms exactly at the interface between HfO 2 and TiN caused a dramatic increase of the work function, thus reconciling computations and experiment.

Carver htr-880 Is Similar To: Sunfire.com Ultimate Receiver Bob Carver Sunfire (40.5% similar) look under products under the hall a fame tab and download the manual. View specs at sunfire.(posted on May 6th, 2016) C-1000 Carver Receiver With Rh (54.5% similar) There is a 10 handling fee for shipping. This is a massive home theater amplifier with multiple digital inputs. The HTR-880 is a high performance receiver built to the sonic standards of Carver separates. Its clean function appearance belies the host of features and innovative audio technologies contained within its precision-crafted chassis. Audio manuals and audio service pdf instructions. Find the user manual you need for your audio device and more at ManualsOnline. Carver Stereo System htr 885.1 owners manual ManualsOnline.com. Carver htr 880 home theater receiver manual. Find best value and selection for your CARVER HTR 880 RECEIVER SERVICE MANUAL search on eBay. New listing Carver HTR-880 Home Theater Receiver With Owners Manual. The HTR-880 is a high performance receiver built to the sonic. Carver Amplifier and Carver Audio Product Specs. Used Carver HTR 880 Home Theater Receiver. CARVER HTR880 Service Manual. Category: HOME THEATER RECEIVER. Format: PAPER. Price: $29.99. Back Add To Cart + Users also viewed. KMOS2150; PM175 PM-175; PM350; THE CARVER RECEIVER MXR150 MXR-150; MXR130; CT6; CMV1185; DIGITAL TIME LENS SERVICE MANUAL; PMX PG2 PG-2 MODULES; THE CARVER RECEIVER MXR130 MXR-130; A760X SERVICE MANUAL; M1.0T.

The origin of this behavior is the different chemical interaction of oxygen vs. Nitrogen with the transition metal atoms Hf and Ti. Changes in the distribution of electronic charges between the HfO 2 and TiN layers at the interface determine the effective work function. This detailed understanding and control of the chemistry at the interface is thus critical to fabrication processes of energy efficient transistors. 2.2 Strength of metal/ceramic interfaces and thermal expansion: Al and Si 3N 4Silicon nitride is a fascinating ceramic material with a wide range of applications including engine parts and ignition systems in cars, ball bearings, for example in wind turbines, in rocket thrusters due to its resistance to thermal shocks, but also in medical orthopedic devices and in the semiconductor industry as insulator and diffusion barrier. As in many practical applications, interfaces play a critical role. An illustrative example in this context is the strength of an interface between aluminum and silicon nitride.shows two models of Al/Si 3N 4 interfaces, namely one with Si-terminated silicon nitride and the other with N-termination.

The models were constructed using the interface building tools of MedeA ® combined with energy minimization performed with VASP, resulting in the structures shown in. As a measure of the strength of the interface, the work of separation is computed from the energy difference between the interface model and the energies of the corresponding free and relaxed surfaces. Atomistic models of Al/Si 3N 4 interfaces. Left panel: Si-terminated, right panel: N-terminated silicon nitride. The computed work of separation is substantially different related to the relatively weak Si-Al interaction compared with the N-Al bonding.The difference between the two models is striking.

While the Si-terminated interface results in a rather weak bonding between the two materials, the presence of N atoms between the surface Si atoms and the Al atoms of the metallic layer leads to a very strong cohesion between silicon nitride and aluminum.The ceramic and the metallic phases have significantly different coefficients of thermal expansion, as shown in. If the interface is formed at ambient temperature, heating of the system will create a high compressive stress within the metallic phase, which is likely to lead to misfit dislocations and partial decohesion. Modeling such a complex non-equilibrium process requires a multi-scale approach, as will be discussed in the last sections of this review. Computed thermal expansion coefficient of Al and Si 3N 4 obtained from ab initio calculations within the quasi-harmonic approximation based on density functional calculations. Note the high thermal expansion of Al compared with that of ceramic Si 3N 4. The thermal expansion is slightly larger in the basal plane of the hexagonal silicon nitride lattice compared with the expansion in the c-direction.Here, the coefficient of thermal expansion is computed on the ab initio level using the so-called quasi-harmonic approximation. From phonon calculations for a range of different lattice parameters one obtains the vibrational entropy.

Combined with the electronic energy this in turn gives expressions for the Gibbs free energy as a function of temperature. As the temperature is increased, the minimum of the Gibbs free energy shifts to larger lattice parameters. Analysis of this temperature dependence gives the coefficient of thermal expansion as used, for example, in the case of Mg 2SiO 4.

Developed by K. Parlinski, the integration and automation of this capability within MedeA ® greatly facilitates this task. 2.3 Design of low-strain cathode materials for Li-ion batteriesThe volume change of active materials that accompanies charge and discharge of Li-ion batteries is a major source of degradation which limits the overall lifetime of such a battery. While a zero-strain anode material exists, namely Li 4Ti 5O 12, there have not been any suitable zero-or low-strain materials for cathodes. By using systematic DFT calculations, three low-strain materials have been found within the class of LiMn xCr yMg zO 4. The most promising materials have been synthesized and characterized by X-ray diffraction and electrochemical techniques.

The results are consistent with the ab initio predictions.This work focused on oxides of the composition LiM 1 xM 2 yM 3 zO 4 crystallizing in the spinel structure. Low-strain compounds were identified by performing systematic calculations exploiting Vegard’s law as shown in for selected structures. All calculations were carried out using VASP in MedeA ® with the PBEsol exchange-correlation functional. Computed cell volume as a function of Li concentration in transition metal oxides with a spinel structure.The DFT calculations also provide detailed insight into the mechanisms resulting in a near zero-strain behavior. A synergistic compensation mechanism underlies the desired property as illustrated in. With increasing Li concentration, the Mg-O bond lengths tend to decrease, the Mn-O bond lengths remain similar, while the Cr-O bonds tend to increase. As a result, the overall volume of the crystal structure changes little upon charging and discharging with Li ions.

2.4 The structure and properties of boron carbideBoron carbide, B 4C, is one of the hardest materials known, close to cubic boron nitride and diamond. Due to these mechanical properties, it is used in applications such as armor and bulletproof vests. In nuclear power reactors boron carbide is used to control the neutron flux due to the high neutron absorption of 10B and the radiation hardness and chemical stability of B 4C.According to the boron-carbon phase diagram, a boron carbide phase exists between approximately 8 at% and 20 at% C with a melting point reaching 2450°C. The crystal structure of boron carbides consists of icosahedra connected with short linear rods of three atoms.

However, the distribution of the C atoms in this structure is far from obvious. Clark and Hoard give a structure for B 4C where the icosahedra consist only of B atoms connected with C-C-C linear rods. For the boron-rich compound B 13C 2 the structure given by Larson shows B 12 icosahedra connected with linear rods of the composition C-B-C.The universal cluster expansion (UNCLE) method based on ab initio calculations with VASP as implemented in MedeA ® offers a unique methodology for the investigation of the distribution of C atoms in boron carbides as a function of C concentration. The result for the B–C system is shown in.

Stable structures of boron carbide as a function of C concentration computed with the cluster expansion method and computed elastic constants.At a concentration of 20 at% (x B = 0.8) the most stable structure consists of icosahedra of the composition B 11C with the connecting rods of C-B-C arrangements. This is consistent with the earlier theoretical work by Mauri et al.

2.5 Optical properties of Y 2O 3The optical properties in the spectral range of visible and ultraviolet light are determined by electronic transitions from occupied to unoccupied states. Quantitative predictions of these states require a level of theory beyond standard density functional calculations. So-called hybrid functionals such as HSE06, offer a practical approach to compute excitation energies. Using this approach in VASP and the optical analysis tools in MedeA ®, the computed refractive index of Y 2O 3 (yttria) is in good agreement with experimental data, as illustrated in.

2.6 Hydride formation in ZircaloyThe formation of zirconium hydrides is of high concern in the operation of nuclear reactors. Corrosion of zirconium alloys used in the core of nuclear power plants produces hydrogen, and a fraction of the hydrogen diffuses into the zirconium material. When the hydrogen concentration exceeds the terminal solid solubility, the excess hydrogen starts to precipitate as hydrides. This process may lead to embrittlement with crack formation due to lower ductility of the hydrides than that of the Zr matrix.VASP as integrated in the MedeA ® computational environment has been employed to study structural, thermodynamic, and elastic properties of the Zr-H system. The computational accuracy of this method is needed to quantify and determine the behavior of hydrogen in Zr.

This becomes clear considering the small energy difference between the octahedral and tetrahedral sites for hydrogen in the Zr lattice. The electronic total energy difference between the sites is computed to be only 5.9 kJ/mol, with the tetrahedral site being energetically favorable. Vibrational effects can readily be added using MedeA ®-Phonon. Inclusion of vibrational effects change the energy difference between the sites to 0.5 kJ/mol at T = 0 K and to 8.6 kJ/mol at 600 K.Using a thermodynamic model of the solution of H 2 into the octahedral and tetrahedral sites, solubility isotherms and terminal solubility of H in Zr can be computed in very good agreement with experimental data. For example, the simulations predict that the γ-hydride phase forms at H–Zr ratios between 1.1 at high temperatures and 1.4 at low temperatures.

The reported existence range of the γ–phase is for H-Zr ratios between 1.1 and 1.5.The calculations also show that the hydrogen solubility increases under tensile strain and decreases under compressive strain. This leads to hydrogen migration and accumulation in expanded regions of the Zr lattice resulting in hydride precipitation. Examples of regions under tensile stress can be at a Zr/ZrO 2 interface, at the front of a crack tip, or even in regions around Zr self-interstitial atoms. Furthermore, hydrogen is attracted to Zr vacancies and voids. The simulations show that up to six hydrogen atoms are strongly bound inside a single Zr vacancy.

Clustering of vacancies into dislocation loops can lead to regions with very high local hydrogen concentration. The simulations show that hydrogen inside the vacancy loops can delay or in some cases even prevent collapse of the loops. Each of these situations lead to regions highly supersaturated with hydrogen and could be potential nucleation sites of zirconium hydrides.A systematic study of the zirconium hydrides has been performed by successively filling tetrahedral sites in the zirconium lattice by hydrogen, probing a large number of configurations for H-Zr ratios between zero (pure α-Zr) up to complete filling of the sites at a ratio of 2.0 (ɛ-ZrH 2). Computation of the elastic properties of the hydrides is conveniently carried out using the automated approach. Some of the hydride structures display elastic instability, such as cubic δ-hydride with full hydrogen occupancy which can be stabilized by introducing vacancies on the hydrogen sites or by a tetragonal distortion into ɛ-ZrH 2. The elastic moduli of the most stable hydrides at each stoichiometry are shown in. The bulk modulus increases almost linearly with hydrogen concentration from pure α-Zr to ZrH 2.

The shear moduli of the hydrides are similar to that of α-Zr while Young’s moduli of the hydrides typically are lower than for α-Zr. The clear exception is ZrH 1.25 which has high elastic moduli. This is identified as a γ-hydride of P4 2/mmc symmetry. Measured high-resolution electron energy loss spectra for 3C-SiC(001)-3 × 2 surfaces exposed to 50 Langmuir of H(D) and computed vibrational frequencies. ).Furthermore, the computed frequencies are also consistent with the notion that Si-H stretch frequencies are shifted to higher values if the Si atoms are bonded to C atoms. Earlier experiments using infrared spectroscopy showed absorption at 2118 and 2140 cm −1 (Δν = 22 cm −1). Computations using the nanotunnel model result in frequencies for the stretch modes Si1a-H and Si3a-H of 2087 cm −1 (not marked explicitly in ) and 2120 cm −1 (Δν = 33 cm −1) as discussed in Ref.

The earlier bridge-bonded model is inconsistent with these experimental data. Thus, ab initio calculations have been essential in the clarification of the remarkable nanotunnel structure of a silicon carbide surface. Left panel: schematic diagram of the energy levels across a stack of semiconducting Si (the channel of the transistor), the gate oxide consisting of SiO 2 and HfO 2, and the TiN gate metal.

To achieve optimal energy consumption of a p-doped CMOS, the Fermi level of the metal has to be aligned with the top of the valence band of the semiconductor. This is achieved by increasing the work function of TiN. Right panels: (a) atomistic model of HfO 2/TiN interface with some N replaced by O; (b) O atoms are replaced by N atoms only at the HfO 2/TiN interface. Panels (c) and (d) show the change of the work function due to the chemical changes in the system.