hi can you send the papers about Mokharestpack which you mentioned here to me through e-mail Thank you.
From: Hongyi Zhao <[email protected]> To: [email protected] Sent: Wednesday, August 3, 2011 2:30 PM Subject: Re: [SIESTA-L] About k_sampling On 08/03/2011 04:18 AM, Guangping Zhang wrote: > Dear Hongyi, > Thank you very much for you reply. > I have known the sampling is done over the reciprocal space. But I am > not sure how to understand the kgrid_Monkhorst_Pack used in SIESTA. > I used to think the first three integers in each line stand for the > number points used for each reciprocal vectors. > If my understand is right, what is the difference between the following > two way to specify the k sampling. > %block LatticeVectors > a 0.0 0.0 > 0.0 b 0.0 > 0.0 0.0 c > %endblock LatticeVectors > %block kgrid_Monkhorst_Pack > 4 0 0 0.0 > 0 4 0 0.0 > 0 0 1 0.0 > %endblock kgrid_Monkhorst_Pack > In this way, 4, 4 and 1 k point are used along each reciprocal vector > which has the same direciton with its corresponding real space vector. > But if I specify like the following: > %block kgrid_Monkhorst_Pack > 4 4 1 0.0 > 0 0 0 0.0 > 0 0 0 0.0 > %endblock kgrid_Monkhorst_Pack > Does it have the same meaning as the first way? > I have read the manual for many times but I yet have difficulties in > understanding it. > Please do help me or give some instructions. This type of thing is more technically trivial generally used for most of DFT-based codes, so we shouldn't expect all of them in the manual ;-) But anyway, siesta is *open source*, i.e., I mean, we have the source at hand - this is the biggest asset which can help us to clarify any of our fuzzy understandings. For your issue in question, the following two papers can be to used to get more in-depth understanding: H.J.Monkhorst and J.D.Pack, Phys Rev B 13, 5188 (1976) J.Moreno and J.M.Soler, Phys Rev B 45, 13891 (1992) In addition, for the implement of kgrid_Monkhorst_Pack in siesta, this file can give you some hints: siesta-3.0-rc2/Src/kgridinit.F Regards > Best > Guangping > 2011-08-03 > ------------------------------------------------------------------------ > Guangping Zhang > ------------------------------------------------------------------------ > 发件人: Hongyi Zhao <[email protected]> > 发送时间: 2011-08-03 14:05 > 主 题: Re: [SIESTA-L] About k_sampling > 收件人: [email protected] > > > On 08/02/2011 11:12 PM, Guangping Zhang wrote: > > Dear Siesta users: > > I now have a puzzle on the k point sampling. > > Before, I usually use a cubic in real space, > > for example: > > %block LatticeVectors > > a 0.0 0.0 > > 0.0 b 0.0 > > 0.0 0.0 c > > %endblock LatticeVectors > > So its corresponding reciprocal space is also a cubic: > > a' 0.0 0.0 > > 0.0 b' 0.0 > > 0.0 0.0 c' > > when I use the k sampling for this kind cell > > %block kgrid_Monkhorst_Pack > > 4 0 0 0.0 > > 0 4 0 0.0 > > 0 0 1 0.0 > > %endblock kgrid_Monkhorst_Pack > > I think it means 4, 4 and 1 k point will be used along a', b' and c' > > will be used. (Am I right?) > > But if I use a non-cubic cell, > > for example: > > %block LatticeVectors > > a1 a2 0.0 > > b1 b2 0.0 > > 0.0 0.0 c > > %endblock LatticeVectors > > so the corresponding reciprocal space is also a non-cubic: > > maybe like the following: > > a1' a2' a3' (say Vector1) > > b1' b2' b3' (say Vector2) > > c1' c2' c3' (say Vector3) > > If I also use a K point sampling like: > > %block kgrid_Monkhorst_Pack > > 4 0 0 0.0 > > 0 4 0 0.0 > > 0 0 1 0.0 > > %endblock kgrid_Monkhorst_Pack > > This time, are 4, 4 and 1 the k points along the reciprocal Vector1, > > Vector2 and Vector3 respectively? > > Maybe, my discription could make someone confused. > > In other words, is the block kgrid represented in real space lattice > > vectors or in reciprocal space vectors or just in cartesian coordinates? > > Any reply will be appreciated. > > Best > > Guangping > > 2011-08-03 > > ------------------------------------------------------------------------ > > Guangping Zhang > See here for some notes: > http://cmt.dur.ac.uk/sjc/thesis_mcg/node24.html > Regards > -- > Hongyi Zhao <[email protected]> > Institute of Semiconductors, Chinese Academy of Sciences > GnuPG DSA: 0xD108493 -- Hongyi Zhao <[email protected]> Institute of Semiconductors, Chinese Academy of Sciences GnuPG DSA: 0xD108493
