![]() ![]() For sc and fcc Pt crystal structures, we use M x M x M of kpoints mesh since sc and fcc crystal structures have the same lattice constant for all three dimensions. We also optimize kpoints for the plane wave set to ensure the convergence of the energy. And then, we determine the optimal cutoff energy when the difference of energy compared to the value obtained from the highest cutoff energy is less than 0.01 eV. Varying the cutoff energy from 300 to 700 eV, we compute the total energy of each Pt crystal structure. The optimal value of cutoff energy for the plane wave set is determined to converge the total energy before the lattice parameter optimization. we also employ On-the-fly generated (OTFG) ultrasoft pseudopotential for Pt to describe the interactions of ionic core and valance electrons, which is set to have a core radius of 2.403 Bohr (~1.27 Å) and use 32 valance electrons with 4f14 5s2 5p6 5d9 6s1 as the electronic configuration. With CASTEP, we use the generalized gradient approximation (GGA) – Perdew Burke Ernzerhof (PBE) as an exchange-correlation functional. For these three crystal structures, we have found the optimal lattice parameter that makes the crystal structure have minimum energy and determined the most favorable crystal structure of Pt comparing cohesive energy.įor the DFT energy calculation, we use material studio with CASTEP calculation package, which is based on a plane wave basis set. The metal crystal can usually have a form of simple cubic (sc), face centered cubic (fcc) and hexagonal close-packed (hcp) crystal structures. DFT is a powerful tool to calculate energy of crystal structures of metals. SingleCrystal provides simulation of key diffraction techniques – Laue, Precession & transmission electron diffraction – with control over sample and instrumental parameters.The main goal of this project is to predict the energetically preferred crystal structure and corresponding lattice parameter of Platinum (Pt) using Density functional theory (DFT). Reciprocal lattice sections can also be visualized, with control over layer height. SingleCrystal 3’s multi-core architecture dramatically accelerates simulation times for massive structures such as proteins. Once the intensity calculation is complete, diffraction patterns can be rotated in real time using the mouse or multi-touch gestures on the trackpad. SingleCrystal can label reflexions, show systematic absences, and lets you measure distances and angles between diffraction spots. You can colour-code your patterns by intensity, wavelength, or even phase angle. Diffraction- and structural data can be browsed and sorted on screen. You can edit lattice parameters and site occupancies – and opt to exclude certain sites from the diffraction calculation. SingleCrystal lets you rotate your (virtual) crystal in real time, using multi-touch gestures (Mac), by clicking-and-dragging with the mouse, clicking toolbar “tilt” controls, or using the keyboard. ![]() Precise tilts can be entered, or you can define a view direction as a plane normal or lattice vector. Other controls allow you to change the scale (camera constant), saturation, sample thickness, wavelength and other parameters. You can use SingleCrystal as a virtual lightbox: just drag-and-drop a diffraction image into any window, zoom in to examine fine details, move or rotate the image. Use the translucent Ruler, Protractor and Grid overlays to measure your pattern and copy the results to the clipboard. Simulated patterns can be superimposed above observed patterns, for direct comparison. With the Grid tool, auto-indexing is a breeze: just position the grid points over your observed pattern (TEM or Precession photos) and let SingleCrystal calculate the best-fit orientation and index your diffraction spots. ![]() To help you navigate through diffraction space, you can take advantage of a live stereographic projection (“stereogram”) which can be displayed on the right-hand side of each diffraction window. The stereogram shows the angular positions of plane normals or lattice vectors (zone axes) plotted as poles and optionally as great circle traces – and is fully customizable. ![]()
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