On Tue, 2015-02-24 at 19:08 +0100, Aritz Leonardo Liceranzu wrote: > So if I understood correctly once the Ecutoff is set, the file > "gvectors.dat" contains the complete list of G vectors inside the > sphere with a radius 4*Ecut where magnitudes such like density can be > safely represented. > > Starting from here, how is the real-space grid generated? I ask this > because for my particular calculation there are around 3000 G > different vectors for a real space grid that has nr1=nr2=nr3=24 > points. > > according to the definition: > r= (i-1)/nr1+(j-1)/nr2+(k-1)/nr3
r= (i-1)*a_1/nr1+(j-1)*a_2/nr2+(k-1)*a_3/nr3, where a_1, a_2, a_3 are the three vectors that generate the lattice > The real space grid is denser than the reciprocal grid, so there has > to be some kind of mapping from one to each other that I am missing. > According to the above transparencies both grids should have equal > amount of points. G = h*b_1 + k*b_2 + k*b_3, where b_1, b_2, b_3 are the three vectors that generate the reciprocal lattice. Negative indices (h,k,l) are refolded to positive one atthe other end of the FFT box. The correspondence between G vectors and (j,k,l) indices is provided by array "nl" Paolo > I could still do (i think) brute force transformations using the > forward and inverse transformations defined in transparency 5 but I if > wanted to use fftw in order to be more efficient, shouldn't they be > the same in size? > > As I said, I would appreciate if somebody could address me a reference > or notes to read where these issues are explained. Thanks! > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
