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 Log Mesh of PAO Date: 2009/11/18 02:28 Name: Liao Chen   Dear Prof.T.Ozaki and OPENMX users,I find that the pseudo-atomic basis functions are generated on Log-mesh,which has form r(i)=exp(xmin + i*dx), and that xmin are -7 for all elements while dx and number of mesh grids are different for each elements. I wonder:1. why xmin are taken as -7?2. how to determine dx and number of mesh grids for each element.Another Question:As far as I know, evaluating two-centre integral in reciprocal space needs tocalculate spherical Bessel transform(SBT):g(k) = int r**2 jl(r) f(r) drI performed SBT using Method proposed by Talman, which calculates SBT on log mesh kappa = ln(k) and the array of values returned also on log mesh:k(i) = exp(kappa_min + i * dkappa);Constraints are dkappa = dx. How to choose kappa_min in order to continue calculationusing values of SBT accurately? I think it should be not too large or too small. Hope for your advice. Sincerely, Liao Chen
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 Re: Log Mesh of PAO ( No.1 ) Date: 2009/12/01 13:19 Name: Masayuki Toyoda  Hi, As for the latter question, I can give you some infomation.I'm working on computation of two-electron integrals and also havingdifficulities in finding optimum parameters for SBT.Basically, I choose parameters simply by trial and error.Note that errors can be estimated by performinig direct and inverse SBT.From my experience, when using N=1024 points, rho0 = kappa0 = -10(where r[i]=exp(rho0+drho*i) and k[j]=exp(kappa0+dkappa*j)) seems toyield good results.My articles are posted on the following page, a part of which relatesto this issue and I hope helps you:http://www.openmx-square.org/exx/index.htmlBest regards,Masayuki ToyodaRCIS/JAIST

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