Dear Marty, Thx for your answering. This morning,I did as you said,by changing as follows:
%block PAO.BasisSizes C DZP -----original set %endblock PAO.BasisSizes *%block PAO.BasisSizes*** *C TZP -----changed(here i tried 'C** T** ZDP',too)* *%endblock PAO.BasisSizes * But,disappoitingly,it still shows the warning of 'not fulfill the f_sum rule'. What should i do to reach the fulfillment of f_sum rule ? * * With my best regards! xiaolin, from ZJU * * 2011/1/18 Marty Blaber <[email protected]> > Hi Lin Xiao, > > The f-sum rule says the integrated oscillator strength should be equal to > the number of electrons. In siesta, the number of available unoccupied > states is limited by the size of the basis set. Increase DZP to TZP or TZDP, > and the f-sum should improve. > > Cheers, > Marty > > On 18 January 2011 07:39, lin xiao <[email protected]> wrote: > >> Dears, >> When i use optical module,it always shows this warning: >> *[yangxu@WimaxServer 20110113-10]$ /opt/siesta-3.0-rc2/bin/input < >> Graphene-optical.EPSIMG* >> * ## 0.000000000000000E+000 19.9999000000000 * >> * ## 1* >> * ## 0.661800000000000 * >> * ## 0.000000000000000E+000* >> *Fsum rule is not fulfilled by more than a 20%* >> * The dielectric function will be extended* >> * to higher energies by enforcing the Fsum rule* >> * This will increase the quality of the quantities* >> * calculated via the Kramers-Kroning relation* >> and here is the explanation of fsum-rule in the optical module: >> If the F-sum rule is not fulfilled by an amount larger than >> certain percentage specified in the program via the parameter THRESHOLD, the >> imaginary part of the dielectric function will be appendedby a tail of the >> form: >> C/w**p >> where C and p are determine to ensure continuity and to enforce the F-sum >> rule.This should increase the quality of the quantities determined via >> theKramers-Kroning relations, however it is not very sophisticated and in >> certaincases it can create pathological problems. Anyway, it can be >> easily desactivated by setting THRESHOLD to zero. >> What should i do to fulfill the f-sum rule? >> Should i reset my parameters in the '.fdf' file(see in the attachment) ? >> >> I am looking forward! >> THX! >> xiaolin,from ZJU >> * >> * >> * >> * >> >> >
