Dear Zhen, I would recommend that you change the cuttof radii in your pseudo and regenerate it (perhaps 2.0 radii for all your channels, but you can play with it). Then test it again for polarization in the bulk. If you never get spin polarization to be zero, try turning on relativistic corrections, and even core corrections. Just be methodic and go for each of these things (radii, relativistic corrections, core corrections) sequentially. The atom manual should be sufficient to guide you in the process. The process should be: Generate your pseudo with atom, run a SIESTA calculation with that one and record the magnetization with a standard basis set, if polarization is not zero, go back and generate a new pseudo, and iterate as needed.
Whenever your polarization is zero, you'll discover that the lattice constant in the bulk should be reasonable; then you can proceed to study phonon dispersions. Best regards, -Salvador. ----- Original Message ----- From: "Zhen Huang" <[email protected]> To: [email protected] Sent: Tuesday, March 2, 2010 8:20:42 PM GMT -05:00 US/Canada Eastern Subject: Re: [SIESTA-L] Fwd: Titanium Phonon Calculation Re: Titanium calculation help posted earlier Dear Salvador- I turned on the spin-polarized. I find the Qup-Qdown is not zero. siesta: Total spin polarization (Qup-Qdown) = 4.856526. I am using GGA PBE generated from http://www.tddft.org/programs/octopus/ pseudo .php Lodger radii 3. I also tried the GGA psf converted from ABINIT which I download from SIESTA website the Qup-Qdown is about 4.939. Can you let me know how can I fix this? Thanks. Best Regards ------- Zhen (Alex) Huang Ph.D. Student Nanoscale Transport Research Group Laboratory for Computational Methods in Emerging Technologies Cooling Technologies Research Center School of Mechanical Engineering Purdue University Tel: 765 237 9733 On Mon, Mar 1, 2010 at 10:14 AM, Barraza-lopez, Salvador < [email protected] > wrote: Hi all, I've been following this post and want to mention something else that has not come out yet. Ti has in the valence two d and two s electrons. d-electrons are responsible for magnetic behavior. So, I'd like to ask: Have you taken your Ti pseudo (is it LDA, GGA pseudo?) and ran a spin-polarized(!) bulk calculation on the HCP phase (two atoms in unit cell) ? Don't worry about the basis now, just use the standard one. If you've done this, is your total spin up minus spin down is equal to zero? Titanium should be non-magnetic. If you get a large spin polarization here, there is no point in keep going further. If you are sure your bulk Ti run is non-magnetic, please disregard my post. Best regards, -Salvador. ----- Original Message ----- From: "Zhen Huang" < [email protected] > To: "SiestaMailingList" < [email protected] > Sent: Monday, March 1, 2010 8:19:00 AM GMT -05:00 US/Canada Eastern Subject: [SIESTA-L] Fwd: Titanium Phonon Calculation Re: Titanium calculation help posted earlier Dear Friends- I had trouble of reply my old post. This is a following question about Titanium. After I increased the kgrid_cutoff to 25 Ang. The results do become better. However, when I am running 3*3*3 supercell calculation the dispersion curve becomes like attached. I am running a 5×5*5 case (on 4 processors) now however, the calculation becomes really slow. I wonder what is the best way to run it faster. Again my input files are attached. Please give me some advice. Further, shall I comment kgrid_cutoff in vibrational properties calculation? I tried it but it gives me totally wrong results. I wonder if I can speed up the calculation by doing anything. I deeply appreciate your help. Best Regards ------- Zhen (Alex) Huang Ph.D. Student Nanoscale Transport Research Group Laboratory for Computational Methods in Emerging Technologies Cooling Technologies Research Center School of Mechanical Engineering Purdue University Tel: 765 237 9733 -- Salvador Barraza-Lopez Postdoctoral Fellow School of Physics The Georgia Institute of Technology Office N205 837 State Street Atlanta, Georgia 30332-0430 U.S.A Tel: (404) 894-0892 Fax: (404) 894-9958
