Re: [SIESTA-L] Fwd: [SIESTA-L] net charge calculation

2007-04-19 Thread Andrei Postnikov
On Thu, 19 Apr 2007, Yurko Natanzon wrote: | Dear Adam Gali, Andrei Postnikov, | thank you for explanation. Actually, I'm not interested in particular | numbers, but want to observe changes in ionic charges of atoms, | neighboring to dopant and the dependence of such changes on a dopant |

Re: [SIESTA-L] net charge calculation

2007-04-19 Thread Yurko Natanzon
ok, there some papers which use Mulliken population with SIESTA. For example, this one: http://arxiv.org/pdf/cond-mat/0008340 The authors say that differences (of net charges and BOP-s) are less sensitive to the choice of basis sets, so they can be meaningful. Can anybody confirm this? On

[SIESTA-L] Fwd: [SIESTA-L] net charge calculation

2007-04-19 Thread Yurko Natanzon
Dear Adam Gali, Andrei Postnikov, thank you for explanation. Actually, I'm not interested in particular numbers, but want to observe changes in ionic charges of atoms, neighboring to dopant and the dependence of such changes on a dopant concentration (comparabale to undoped system). Is it

Re: [SIESTA-L] net charge calculation

2007-04-19 Thread Adam Gali
Dear Yurko Natanzon, take care! Mulliken-charges could be meaningless by using diffusing orbitals. Draw the net charge density around the atoms (you can do it by SIESTA and utility programs provided with) and you can see that O is negatively polarized while Si is positively polarized

Re: [SIESTA-L] net charge calculation

2007-04-19 Thread Andrei Postnikov
On Thu, 19 Apr 2007, Yurko Natanzon wrote: | Well, this works for TiO2, but when I tried to do it with SiO2, I've got: | | then oxygen has positive ionic charge (6-5.987), and silicon has | negative (4-4.026). Does it make any sense?? Dear Yurko: they have no more sense than ionic charge in

Re: [SIESTA-L] net charge calculation

2007-04-19 Thread Yurko Natanzon
Well, this works for TiO2, but when I tried to do it with SiO2, I've got: mulliken: Atomic and Orbital Populations: Species: Si Atom Qatom Qorb 3s 3s 3py 3pz 3px 3py 3pz 3px 3Pdxy 3Pdyz 3Pdz2 3Pdxz 3Pdx2-y2 1 4.026 0.404

[SIESTA-L] net charge calculation

2007-04-19 Thread Yurko Natanzon
Dear SIESTers, I wonder how to calculate net ionic charge with SIESTA. For example, I have TiO2 anatase supercell with 12 atoms. Pseudopotential for Ti has valence electrons in 3s2 3p6 3d2 4s2 (12 electrons), O has 2s2 2p4 (6 electrons). Then i set WriteMullikenPop 2 and obtain 10.972 for each Ti

Re: [SIESTA-L] how to dope a hole or electron in a bulk crystal?

2007-04-19 Thread Bozidar
Hi all, I forgot to mention that there is really a problem of infinite array of charged supercells if NetCharge is set to +1 or -1 when periodic boundary conditions are used. But there are terms which can overcome this problems if for example formation energies are calculated. Bozidar

Re: [SIESTA-L] how to dope a hole or electron in a bulk crystal?

2007-04-19 Thread Bozidar
Hi everyone, I think connected to this problem is evaluation of donor or acceptor levels in doped materials. So if you want to find donor level you should use something like: X(0/+) = R(0/+) + [E(X0) − E(X+)] − [E(R0) − E(R+)] where R(0/+) is donor level of reference state (this is known

Re: [SIESTA-L] how to dope a hole or electron in a bulk crystal?

2007-04-19 Thread Wang kunpeng
Hi, Artyukhov, Do you mean that we need not set extra options in fdf file? But what´s the difference to the neutral states? can you give more detail instruction about AUTOMATIC? Thank u very much!! K.P.Wang 2007/4/19, Vasilii Artyukhov [EMAIL PROTECTED]: I guess this is more or less

Re: [SIESTA-L] how to dope a hole or electron in a bulk crystal?

2007-04-19 Thread Wang kunpeng
Thank u very much! John. Yes, impurity doping is one way, but generally it needs a large supercell. So we can add the desired concentration of holes or electrons to the bulk system instead of the impurity doping. As u mentioned that P doping in bulk Si, we can also add the desired concentration

[SIESTA-L] how to dope a hole or electron in a bulk crystal?

2007-04-19 Thread Wang kunpeng
Hi, All: how to dope a hole or electron in a bulk crystal? I set the option: NetCharge=-1: as the castep do, that I supposed to dope a electron in a peoridic system. But the DOS I calculated is very different to the literature. Can u tell me what´s the problem? Thank u very much!! Yours

[SIESTA-L] spin contamination

2007-04-19 Thread Rainer Hoft
Dear Siesta users, I have a question with regards to spin contamination, yet I'm not sure if this is the correct terminology to use in my context. SIESTA gives as part of its output the spin polarisation, SP= Q_up - Q_down. So for a singlet this is 0, for a doublet 1, a triplet 2 etc. But