The symmetry keywords cubic, fcc, bcc, tetragonal, tetragonal, One useful output option is -symmetry which attempts to label the high symmetry points using the conventional Brillouin zone notation The options -np, -ps, -eps behave exactly as for dos.pl. The -nj option (“no-join”) disables the crossing detection even when the input file is a. Time consuming and take several minutes to complete in large cases, so patience is sometimes required. phonon fileĬontains eigenvector information, so only in this case is crossing detection enabled. Matching of eigenvectors at adjacent points to determine branch connectivity. High-quality dispersion plot requires that phonon branches are drawn as continuous lines even when twoīranches cross in between the computed wavevectors. Unlike the behaviour of dos.pl there is an important difference between theīehaviour when reading these two different output files concerning the detection of branch crossings. phonon file and generate a dispersion curve With a slightly shifted baseline, scaled, and legends added. Infrared spectrum andĭOS curves based on just the TO modes or TO plus LO have been combined into into one plot The -lorentz option switches from Gaussian toĪ Lorentzian broadening and the -temp T option sets the temperature for the Stokes thermal populationįigure 3.1 shows an example derived from the output produced by using dos.pl on the example runįigure 3.1: Example output from dos.pl based on the run of figure 2.3. More realistic model spectrum than in the infrared case. TheĬomputed spectrum does include the frequency-dependent and Stokes thermal factors, and is therefore a Likewise the -raman option extracts raman intensities and computes the weighted spectrum. Model of an infrared powder spectrum, and should be regarded as a simple approximation This simple algorithm is not a fully realistic The option -ir option weights the computed DOS by the computed These files are written to standard output so use a shell redirect The options -np, -ps, -eps change the default output and write an xmgrace file, a PostScript orĮncapsulated PostScript file respectively. cell file if %BLOCK PHONON_KPOINT_LIST was Over all q-points present in the file, using the weights generated by CASTEP in the case of The DOS is constructed as a weighted average Will generate a phonon density of states using a Gaussian broadening with a FWHM of 10 cm - 1,Īnd invoked xmgrace to generate the plot. Arguments are given in “unix style” following a minus sign (dash). phonon file and generate a phononĭensity of states plot. Interpreter and an X-windows server (Xmgrace is an X-windows program and requires a running X server Part of the “cygwin” suite of programs ( ) along with shells, the PERL Xmgrace is also available for Microsoft Windows systems as Installed using the system package manager. On linux systems xmgrace can usually be found as a contributed package and ( ) (the perl programs generate an xmgrace script and Generation of the graphics output is handled by the “xmgrace” program These programs are written in the PERL language which is almost universally available on modern phonon files, read the phonon informationĪnd can generate plots of phonon dispersion curves across the Brillouin Zone, and of phonon densities of states Chapter 3Īdditional tools and programs are available to help automate post-processing analysis and plotting of the Plutonium (Pu) is well known to have complex and unique physico-chemical properties. Systematic HRIXS experiments as a function of temperature and concentration in the fcc Pu-Ga alloys are underway. These differences are significant and thus provide a framework for refined theoretical treatments. We have designed and successfully employed a novel microbeam on large grain sample concept to conduct high resolution inelastic x-ray scattering (HRIXS) experiments to map the full phonon dispersion curves of an fcc branch, the energy maximum of the T mode s and the softening of the calculated T branch near the X point, which is not observed experimentally.
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