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Magnetic moment in cubic SrRuO3 Date: 2006/11/02 01:29 Name: JessK Hi, I am trying to find the basis which will describe very well SrRuO3 systems. For testing I chose cubic SrRuO3, perovskite structure, 5 atoms. It is known from planewave calculations and from the literature, that magnetic moment of Ru should be 1.1 - 1.6 mB. I got ~ 0.8 mB with basis : Sr Sr8.0-s2p2d1 Sr_CA Ru Ru8.5-s2p2d2 Ru_CA O O5.0-s2p2d1 O_CA 250 Ry energy cutoff, 14x14x14 kpoint mesh. Any ideas? Is this basis set good? Thanks, JK

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Re: Magnetic moment in cubic SrRuO3 ( No.1 ) Date: 2006/11/04 01:41 Name: T.Ozaki Hi, Have you tried to evaluate the magnetic moment by the Voronoi scheme ? Also, did you check the band dispersion ? Since the cutoff radii of basis function you used are relatively longer for bulk systems, I am wondering that you encountered the overcompleteness. Above all the possibilities are not your case, the discrepancy may be attributed to the pseudopotentials. Regards, TO Re: Magnetic moment in cubic SrRuO3 ( No.2 ) Date: 2006/11/04 06:32 Name: JessK Hi, thank you for the reply. There was an error in my previous message, indeed I used O5.0-s2p1 for oxygen. When I used O5.0-s2p2d1 I got magnetic moment of 1.01mB on Ru atom, and fitted lattice constant is equal to experimental one. >Since the cutoff radii of basis function you used are relatively longer >for bulk systems, I am wondering that you encountered the overcompleteness. How to define is there overcompleteness? I see that program 'polB' can check it. When I run it, the code passed this step, so I think I avoided overcompleteness. Am I wrong? Thanks, JK Re: Magnetic moment in cubic SrRuO3 ( No.3 ) Date: 2006/11/05 00:05 Name: T.Ozaki Hi, When some of eigenvalues, E, of the overlap matrix become minums, the basis set is overcomplete. Since the orthogonal trasformation requires the calculation of 1/sqrt(E), such a trasformation is ill-defined. Even if E is not minus, for a small E the calculation of 1/sqrt(E) produces numerical error. In this case, the eigenvalues of the Kohn-Sham eq. tend to be erratic, and such erratic eigenvalues can be found in the band dispersion. Or if you monitor the eigenvalues during the SCF calc, then you will see the erractic eigenvalues. For cluster or molecular systems, the state with a small eigenvalue can be eliminated. However, the eigenvalue spectrum of the overlap matrix is continuous for the band calculation, and it is not easy to remove ill-conditioned states unfortunately. Regards, TO

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