[Wien] Calculation fo difference of Fermi energies between tantalum and mercury telluride
Dear Prof. Blaha, I formed Slab structures for Ta and HgTe (attached .struct files) and ran WIEN2k 21 version. From the output (.scf files), I find that the work function for Ta and HgTe are similar. However, I am interested to know their difference of Fermi energies. I cannot determine the zero energy of the calculation in the two cases. I shall think that the Fermi energy of Ta (a metal) would be significantly higher than that of HgTe ( an insulator). Could you kindly help me in determining the difference of Fermi energies of Ta and HgTe? With best regards Amlan RayVariable Energy Cyclotron CenterKolkata, India Ta_slab_2.struct Description: Binary data HgTe_slab_2.struct Description: Binary data ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Fermi Energy Calculation using WIEN2k
Dear Prof. Blaha, I am asking you a question about the Fermi energy given by WIEN2k code in .scf output file. For metals, it gives a positive energy similar to what one expects from a free electron gas model (assuming the entire energy is kinetic energy). The calculated Fermi energy will depend on the reference point (zero energy). I think WIEN2k's reference point is the energy at the surface of overlapping Muffin-tin spheres. Since the electronic wave function at the surface of the overlapping Muffin-tin spheres matches with a plane wave function that is assumed for the electrons in the interstitial space, this reference point would define the energy of the lowest occupied single particle state for the electrons in the interstitial space in the context of the calculation. That means the Fermi energy calculated by the WIEN2k code (as given in .scf output file) is the energy difference between the highest occupied state in the interstitial space (Fermi level) and the lowest occupied state for the electrons in the interstitial space. This will be a positive energy similar to the Fermi energy obtained from a free electron gas model, however, of course, the Fermi energy calculated by WIEN2k code would include potential energy contribution also. Please let me know if this interpretation is correct. With best regardsAmlan RayVariable Energy Cyclotron CenterKolkata, India ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Total electron-electron potential in WIEN2K
Dear Prof. Blaha, I use WIEN2K to calculate electron density at the nucleus under compression of the lattice. WIEN2K uses a point nucleus and generally predicts very small effect. Recently using another code that uses a finite nucleus, I found that the electron density at the nucleus (in the case of relatively large indium nucleus) could increase by a factor of two more than the prediction from a pointlike nucleus under the effect of compression. So the effect of finite nucleus seems to be important for such calculations at least for large nuclei. However that code uses independent electron model (i.e. ignores electron-electron repulsion potential)and puts the atom in an impentrable enclosure and reduces the size of the enclosure to study the effect of compression on the atom. I want to put in that code a realistic electron-electron repulsion potential from WIEN2K code so that it can use a quasi-DFT wave function. I think I can get a Table of electron-electron potential as a function of distance from the nucleus using WIEN2K code. However somehow I could not generate it. I request you kindly to send me the procedure to generate total electron-electron potential as a function of distance from the nucleus within the muffintin sphere of the atom. I am running an older version (WIEN2K 9.0) of WIEN2K. With best regards Amlan Ray Variable Energy Cyclotron Center Kolkata India ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Effect of finite nucleus on the rate of change of electron capture rate with external pressure
I actually performed non-relativistic calculations earlier for 7BeO case. However I think very close to the nucleus, relativistic effects are important even for beryllium. I performed non-relativistic calculations for different values of R0 (R0=0.0001 BU, 0.1 BU, 0.4 BU) and found that the value of the electron density becomes somewhat different from the relativistic calculation at the same R0. For different values of R0, the electron density changes as expected for non-relativistic calculation also. However the rate of change (K_P) of the fractional electron density (Delta_Lambda/Lambda) with the external pressure remains the same whether relativistic or non-relativistic calculation is done and is also independent of R0. I think for a finite nucleus, the result should be different, because the character of the wave function (both radial and Z-dependence) should change and I think calculated K_P will increase. I also think that for calculating the electron density at the nucleus, relativistic effects are important, even for a light nucleus. With best regards Amlan Ray VECC, Kolkata, India___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Effect of finite nucleus on the change of electron capture decay rate under compression
I tried different values of R0 (R0=0.0001 BU, 0.1 BU, 0.4 BU) for calculating the electron density at the nucleus. Of course, the electron density changes for different values of R0 and so the predicted electron capture rate also changes. However I am not trying to compare the calculated electron capture rate with the experimental result. By taking a suitable average over R0, I can probably get a good agreement between WIEN2K calculation and the experimental result. However I am interested to calculate the rate of increase of the electron density at the nucleus under compression. As I compress 7BeO lattice, the fractional change of the electron density at the nucleus (Delta_Lambda/Lambda) increases linearly with the applied external pressure. This result was obtained from both WIEN2K calculations and experiment. However the slope of the staright line (Delta_Lambda/Lambda versus Pressure plot) is very different for WIEN2K calculation and experimental result. From WIEN2K calculation, I get K_P=0.42X10^-4 (GPa)^-1, whereas expt result is K_P=(2.2+-0.1)X10^-4 (GPa)^-1. The calculated value of K_P is essentially independent of R0. I tried different values of R0 and do not find any change in the calculated value of K_P. So naturally taking average over R0 will not change K_P. It is very robust. However the consideration of a finite nucleus will change the character of the wave function ( both radial and Z-dependence) within the nuclear volume. So I think the consideration of a finite nucleus will change the calculated value of K_P and it should increase the value bringing it closer to the experimental number. Isomer shift is not directly proportional to the electron density at the nucleus and people tune the calculations using experimental results. In the case of isomer shift, I am interested to know how well WIEN2K calculations agree with the change of isomer shift under compression. Please refer me to a suitable publication where the change of isomer shift under compression has been studied. With best regards Amlan Ray VECC, Kolkata India___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Effect of a finite nucleus on electron density at the nucleus
Dear Prof. Blaha, I use WIEN2K code for calculating electron density at the nucleus to determine the change of electron capture nuclear decay rate in different environments. WIEN2K uses a point nucleus and I use the value of the electron density at the first mesh point as given by the code. I am interested to know the effect of the finite size of the nucleus on the electron density at the nucleus. Since Dirac wavefunction of s-electron becomes infinity at r=0 for a point nucleus, the effect of considering a finite nucleus could be significant for calculating the electron density at the nucleus. I was wondering if the effect of a finite nucleus might be included in an upcoming version of WIEN2K. Please let me know if there is any such plan. With best regards Amlan Ray Variable Energy Cyclotron Center Kolkata, India___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
[Wien] Charge density plot for s-valence electrons
Dear WIEN2K users, I want to create a charge density plot for s-valence electrons (charge density versus distance from the corresponding atomic nucleus) and need help in this regard. Starting with case.clmval file, I can create charge density plot for all the valence electrons together?using lapw5. But I am interested to seperate out only the valence s-electron contribution. Can someone help me in this regard? I am using WIEN2K9.1 version. ? With best regards ? Amlan Ray Address ? Amlan Ray Variable Energy Cyclotron Center 1/AF, Bidhannagar Kolkata - 700064 India -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20101206/91f24631/attachment.htm
[Wien] charge density plot for s-valence electrons
Dear WIEN2K users, I want to create a charge density plot for s-valence electrons (charge density versus distance from the corresponding atomic nucleus) and need help in this regard. Staring with case.clmval file, I can create charge density plot for all the valence electrons together?using lapw5. But I am interested to seperate out only the valence s-electron contribution. Can someone help me in this regard? I am using WIEN2K9.1 version. ? With best regards ? Amlan Ray Address ? Amlan Ray Variable Energy Cyclotron Center 1/AF, Bidhannagar Kolkata - 700064 India -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20101201/e95011f6/attachment.htm
[Wien] Electron density at the nucleus (electron capture nuclear decay rate work)
Dear Prof. Blaha, Thank you very much for the detailed explanation regarding the treatment of the core 1s state of Be. I can now understand much better how?the calculation for the core state?is being done. If there is any paper or document describing the treatment of the core state in detail, then please give me the reference. As a beginner, I still have a few questions and shall be grateful for your reply. ? 1) My understanding was that the total potential (electrostatic and exchange) inside a lattice approximately looks like a Muffin tin potential. For example, in the interstitial region, the electrostatic fields of the neighboring ions should approximately cancel out producing approximately a constant potential (zero field) region. I understand there is some fuzziness or arbitrariness in the determination of Muffin tin radius RMT and that part has no physical significance, but the overall picture of Muffin tin potential inside a lattice should have physical significance. Are you also saying the same thing? ? 2) I did not know earlier that 1s wave function is seeing a continuous potential and?the potential?is continuing with a 1/r tail outside the Be sphere. However this would mean that 1s electrons are seeing the potential of a single Be ion outside RMT. But will not the potential outside the Be sphere be approximately constant because of the presence of other Be ions? If 1s and 2s electrons see different potentials outside the Be sphere, then they would not be orthogonal to each other. ? 3) I have done calculations by treating both 1s and 2s states of Be as valence states, but I have not really understood how the code actually handled the situation. I understand that both 1s and 2s electrons will see the same complete potential inside the Be sphere and there would be spherical harmonic solutions. But outside the Be sphere, 2s electrons are seeing the potential of the interstitial region and are treated as approximately plane waves with a matching boundary condition at RMT. ? How will 1s electrons be treated outside the Be sphere, when they are also considered as valence electrons? They should also see the same constant potential in the interstitial region, but probably because of their higher energy should not be treated as plane waves. There would be the question of boundary condition at RMT for 1s valence electrons also. ? The absolute value of the total electron density at R0 increases by 0.07% to 0.14% if 1s is treated as a core state compared to as a valence state for Be. However the change of total electron density for Be?at R0 for the compressed versus normal BeO lattice cases remain essentially the same whether we treat 1s as core or valence state. ? 4) The energy of 1s core state always increases due to the compression of BeO lattice. From the?physical point of view, I thought that the energy?was increasing because the electrons?were confined to a smaller region due to the compression. If the 1s electrons are spreading out, then what are the physical?reasons for the increase of the energy of 1s electrons. ? With best regards Amlan Ray Address Variable Energy Cyclotron Center 1/AF, Bidhan Nagar Kolkata - 700064 India? -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100427/5d353a99/attachment.htm
[Wien] Electron density at the nucleus (Electron capture nuclear decay rate work)
I have been reading all the messages about the electron density at the Be nucleus under compression and would like to say a few things. My background is in experimental nuclear physics and I am very interested to undertsand quantitatively the results of electron capture experiments in compressed material. WIEN2K is probably the best availabale code at this time for this purpose. Given my background, please excuse me if I make any incorrect statements. I shall be grateful if you would kindly point out my mistakes. ? 1) Let me start with the Physics justification for thinking why Be 1s wave function should satisfy boundary conditions at the muffintin radius RMT(Be). As I understand, in this model, 1s electrons are seeing scf-potential of the crystal only within the Be sphere. Outside the Be sphere, it should see the potential of the interstitial region. Since there is an abrupt change of potential at the muffintin radius RMT(Be), so the wave function inside and outside the Be sphere should be different and there should be a matching boundary condition at RMT(Be). If we assume that outside the Be sphere, the 1s wave function should be that of a free Be ion, then it should be matched with the core wave function inside the Be sphere at RMT(Be). As a gross oversimplification, I suggested that the 1s wave function outside RMT(Be) might be taken as zero, because I thought that would be relatively easy to implement.(But I agree it was a?wrong boundary condition.)??However ?my main point is that the core wave function inside and outside the Be sphere should be different and there should be boundary conditions at RMT(Be). ? 2) I think whether compression would delocalize 1s wave function?should depend on the boundary condition applied. If the only boundary condition is that the core wave function would be zero at infinity, then of course, it will delocalize under compression. But probably there should be boundary conditions at RMT(Be). ? 3) I certainly agree that the tail of 1s wave function would experience more attractive potential when BeO is compressed. But I think that would affect the core wave function outside the Be sphere. It is not clear to me how that would affect the core wave function inside the Be sphere, particularly near the nucleus. The potential inside and outside the Be sphere is different and the wave functions should, in general, be different with a matching boundary condition at RMT(Be). ? 4) I certainly agree that the?contraction of 2s orbital would drive 1s orbital into expansion. But the reduction of 1s electron density at the nucleus is essentially independent of the muffintin radius used. I have done calculations of normal and compressed BeO cases keeping RMT(Be) the same in both the cases and have also done calculations by reducing RMT(Be) for the compressed case only. The change of 1s electron density at the nucleus remains the same always. The change of valence electrons in Be sphere is only 0.01 electrons and I can vary this number by adjusting RMT(Be). But that did not affect the change of 1s electron density at the nucleus. s-valence electrons in Be sphere can be made smaller?for the compressed case by adjusting RMT(Be), but still the result did not change. So I think that the effect of 2s orbital contraction on 1s electron density at the nucleus is probably very small. ? 5) I know about three experiments (done by different people) where the increase of electron capture rate by nuclei under compression?was seen and the effect is much more than expected from valence electrons. ? With best regards Amlan Ray Address Variable Energy Cyclotron Center 1/AF, Bidhan Nagar Kolkata - 700064 India -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100423/1bc4d143/attachment.htm
[Wien] electron density at the nucleus (Electron capture nuclear decay rate work)
of electron density at the nucleus of 109In and 110Sn implanted in small Au lattice versus large Pb lattice (A. Ray et al., Phys. Lett B679, 106 (2009)). We have discussed this method of calculation in our paper, but it is very empirical without much theoretical grounding. ? TB-LMTO treats atomic core states? as frozen. I am interested to know about the core state wave function calculation of WIEN2K? and whether the calculation is agreeing with the density functional calculations of compressed atoms that have been done so far. ? With best regards Amlan Ray Address: Variable Energy Cyclotron Center 1/AF, Bidhan Nagar Kolkata - 700064 India Your Mail works best with the New Yahoo Optimized IE8. Get it NOW! http://downloads.yahoo.com/in/internetexplorer/ -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100407/ec6b555b/attachment.htm
[Wien] Electron density at the nucleus
Dear Prof. Blaha, I have run BeO lattice case (space group P63mc) using WIEN2K code and found that the Be 1s state energy is = -6.204169219 Ry and the electron density at Be nucleus (RTO001) due to 1s core state is = 34.428627. Then the code was run again by reducing the BeO lattice parameters by 5%. As a result, Be 1s state energy increases to -5.971227606 Ry as qualitatively expected from uncertainty principle considerations. The core force also increases as expected and the total charge in sphere 1 also increases by about 0.3%. However as a result of the compression, the electron density at the nucleus due to the core 1s state decreases to 34.331679 from the earlier value of 34.428627 by about 0.3%. This result looks puzzling. As a result of compression, the kinetic energy of Be 1s state should increase and the 1s state electrons should be confined to a smaller volume thus increasing the electron density at the nucleus. The electron density of 2s states of Be at the nucleus increases due to the compression as expected. So the puzzle is why the electron density of the core 1s state of Be is decreasing due to the compression. The result given by WIEN2K also disagrees (by a factor of 5-6) with the experimental result regarding the observed increase of electron capture rate of 7BeO under compression. I am interested to know how the calculation regarding the electron density at the nucleus is being done in WIEN2K code and what are the relevant subroutines to look at. If there is any published literature then please also refer me to those papers. With best regards Amlan Ray Address Amlan Ray Variable Energy Cyclotron Center 1/AF, Bidhna Nagar Kolkata - 700064 India Your Mail works best with the New Yahoo Optimized IE8. Get it NOW! http://downloads.yahoo.com/in/internetexplorer/ -- next part -- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20100402/b3fcc0e2/attachment.htm
