Dear everyone and Stefano,<br><br>In order to find the reason for the problem, I changed some parameters in the input file to print out the occupation number for each atom as following:<br><br> &control<br> calculation='scf'<br>
restart_mode='from_scratch',<br>
prefix='Gd',<br> pseudo_dir = './'<br> outdir='./',<br> /<br> &system<br> ibrav= 4, celldm(1)= 6.96, celldm(3)= 1.59,<br> nat= 2, ntyp=2,<br> nspin = 2,<br> starting_magnetization(1)=1.0,<br>
starting_magnetization(2)=1.0,<br> ecutwfc=55.0,<br> ecutrho=220.0,<br> occupations ='smearing',<br> smearing ='gauss',<br> degauss = 0.01,<br> lda_plus_u = .true.<br> Hubbard_U(1)= 1.d-20<br>
Hubbard_U(2)= 1.d-20<br> /<br> &electrons<br> diagonalization='david',<br> mixing_beta = 0.3,<br> conv_thr = 1.0d-6,<br> electron_maxstep = 400,<br> /<br>ATOMIC_SPECIES<br> Gd1 1.0 Gd.GGA-PBE-paw.UPF<br>
Gd 1.0 Gd.GGA-PBE-paw.UPF<br>ATOMIC_POSITIONS {crystal}<br>Gd1 0.00000000 0.00000000 0.00<br>Gd 0.33333333 -0.33333333 0.50<br>K_POINTS {automatic}<br>2 2 2 0 0 0<br><br>I searched the occupation number for each atom In the output file, and found following information:<br>
<br>At the beginning:<br><br><span style="background-color:rgb(255,0,0)">atom 1 Tr[ns(na)] (up, down, total) = 7.00000 0.00000 7.00000</span><br>atom 2 Tr[ns(na)] (up, down, total) = 7.00000 0.00000 7.00000<br>
<br>However, after the first iteration, I found the occupation number of the first atom is totally wrong as following:<br><br><span style="background-color:rgb(255,0,0)">atom 1 Tr[ns(na)] (up, down, total) = 7.00064 5.60439 12.60503</span><br>
atom 2 Tr[ns(na)] (up, down, total) = 6.87289 0.00836 6.88125<br><br>At the last iteration, I found:<br><br><span style="background-color:rgb(255,0,0)">atom 1 Tr[ns(na)] (up, down, total) = 3.60781 3.88818 7.49599</span><br>
atom 2 Tr[ns(na)] (up, down, total) = 7.00165 0.09767 7.09932<br><br>So, I think the reason for unphysical results is due to the wrong occupation number for the first atom. However, when I set these two atoms into antiferromagnetic, their occupation number are correct. Could you give me some suggestions?<br>
<br>Best regards,<br>Kun Tao<br>
<br><br>On 14 March 2013 05:54, Stefano de Gironcoli <<a href="mailto:degironc@sissa.it" target="_blank">degironc@sissa.it</a>> wrote:<br>> dear Kun Tao<br>><br>> the 3D visualization of the up-down charge density in the different<br>
> cells you have studied should probably clarify to you what the system is<br>> trying to teach you.<br>><br>> stefano<br>><br>> On 03/13/2013 10:36 PM, 琨陶 wrote:<br>>> I try to force two Gd atom into ferromagnetic with following parameters:<br>
>><br>>> nat= 2, ntyp=2,<br>>> starting_magnetization(1)=1.0,<br>>> starting_magnetization(2)=1.0,<br>>><br>>> ATOMIC_SPECIES<br>>> Gd1 1.0 Gd.GGA-PBE-paw.UPF<br>
>> Gd2 1.0 Gd.GGA-PBE-paw.UPF<br>>> ATOMIC_POSITIONS {crystal}<br>>> Gd1 0.33333333 0.66666667 0.25<br>>> Gd2 0.66666667 0.33333333 0.75<br>>><br>>> And I got the following results:<br>
>><br>>> total magnetization = 7.55 Bohr mag/cell<br>>> absolute magnetization = 8.02 Bohr mag/cell<br>>><br>>> In this case, even the "absolute magnetization" is wrong. And the<br>
>> magnetic moments on two atoms are 0.47, 7.08, respectively, which are<br>>> are away from the experimental results 7.8 for each atom.<br>>><br>>> I do not know the reason, perhaps there is a small bug in the code for<br>
>> 4f elements or due to some incorrect parameters in my input file. Any<br>>> suggestion is appreciated!<br>>><br>>> With regards,<br>>> Kun Tao<br>>><br>>> On 13 March 2013 12:35, mohnish pandey <<a href="mailto:mohnish.iitk@gmail.com" target="_blank">mohnish.iitk@gmail.com</a>> wrote:<br>
>>> Did you try using different initial spin configurations? If your interested<br>>>> in FM ground state then may be you should try initial magnetic configuration<br>>>> as FM. e.g. +1, +1 for both.<br>
>>><br>>>><br>>>> On Wed, Mar 13, 2013 at 9:03 PM, 琨陶 <<a href="mailto:taokun76@gmail.com" target="_blank">taokun76@gmail.com</a>> wrote:<br>>>>> Thank you for your suggestions. When I set two atoms in the unit cell<br>
>>>> to be antiferromagnetic, the "total magnetization" is nearly zero, and<br>>>>> the "absolute magnetization" is about 14.67. And the magnetic moment<br>>>>> for two atoms are about 7.16 and -7.18, which is more or less<br>
>>>> acceptable.<br>>>>><br>>>>> Now, the question is that why "total magnetization" and "absolute<br>>>>> magnetization" differs so much if I want to force two atoms into a<br>
>>>> ferromagnetic configuration.<br>>>>><br>>>>> Any suggestions? Thanks!<br>>>>><br>>>>> With regards,<br>>>>> Kun Tao<br>>>>><br>>>>><br>
>>>> On 13 March 2013 11:14, Andrei Malashevich <<a href="mailto:andrei.malashevich@yale.edu" target="_blank">andrei.malashevich@yale.edu</a>><br>>>>> wrote:<br>>>>>> If you want to model antiferromagnetic structure, you should define two<br>
>>>>> types of atoms, Gd1 and Gd2.<br>>>>>> Change ntyp to 2. Use, e.g.,<br>>>>>> starting_magnetization(1)=1.0<br>>>>>> starting_magnetization(2)=-1.0<br>>>>>><br>
>>>>> ATOMIC_SPECIES<br>>>>>> Gd1 1.0 Gd.GGA-PBE-paw.UPF<br>>>>>> Gd2 1.0 Gd.GGA-PBE-paw.UPF<br>>>>>> ATOMIC_POSITIONS {crystal}<br>>>>>> Gd1 0.33333333 0.66666667 0.25<br>
>>>>> Gd2 0.66666667 0.33333333 0.75<br>>>>>><br>>>>>><br>>>>>> On Wed, Mar 13, 2013 at 11:05 AM, 琨陶 <<a href="mailto:taokun76@gmail.com" target="_blank">taokun76@gmail.com</a>> wrote:<br>
>>>>>> Hi,<br>>>>>>><br>>>>>>> Yes, the bulk Gd without Hubbard U is antiferromagnetic. If I set the<br>>>>>>> two atoms in the unit cell to be antiferromagnetic, the "total<br>
>>>>>> magnetization" should be equal to zero, and the "absolute<br>>>>>>> magnetization" is what I have gotten. Now, however, the "total<br>>>>>>> magnetization" is not zero. Could you give me some suggestions?<br>
>>>>>> Thanks!<br>>>>>>><br>>>>>>> With regards,<br>>>>>>> Kun Tao<br>>>>>>><br>>>>>>> On 13 March 2013 10:48, Stefano de Gironcoli <<a href="mailto:degironc@sissa.it" target="_blank">degironc@sissa.it</a>> wrote:<br>
>>>>>>> are you sure you are defining the correct magnetic structure ?<br>>>>>>>> is Gd maybe antiferromagnetic ?<br>>>>>>>> stefano<br>>>>>>>><br>
>>>>>>> On 03/13/2013 03:19 PM, 琨陶 wrote:<br>>>>>>>>> Dear everyone,<br>>>>>>>>><br>>>>>>>>> I want to calculate the magnetic properties of bulk Gd whose<br>
>>>>>>>> magnetic<br>>>>>>>>> moment is about 8 Bohr magneto/atom. Usually, in the output file<br>>>>>>>>> values of "total magnetization" and "absolute magnetization" should<br>
>>>>>>>> be<br>>>>>>>>> nearly the same. However, in my output file, I found a big<br>>>>>>>>> difference<br>>>>>>>>> between them as following:<br>
>>>>>>>><br>>>>>>>>> total magnetization = 8.00 Bohr mag/cell<br>>>>>>>>> absolute magnetization = 15.72 Bohr mag/cell<br>
>>>>>>>><br>>>>>>>>> The good news is that the "absolute magnetization" is close to the<br>>>>>>>>> experimental results (7.86 Bohr mag/atom), the bad news is that the<br>
>>>>>>>> "total magnetization" is wrong. Moreover, when I try to calculate<br>>>>>>>>> the<br>>>>>>>>> magnetic moment on each atom with projwfc.x program, I got about 4.1<br>
>>>>>>>> Bohr mag/atom.<br>>>>>>>>><br>>>>>>>>> Could you give me some suggestions? Any advice are appreciated,<br>>>>>>>>> thanks!<br>
>>>>>>>><br>>>>>>>>> Regards,<br>>>>>>>>> Kun Tao<br>>>>>>>>><br>>>>>>>>><br>>>>>>>>> Attached below is the input file:<br>
>>>>>>>><br>>>>>>>>> &control<br>>>>>>>>> calculation='scf'<br>>>>>>>>> restart_mode='from_scratch',<br>
>>>>>>>> prefix='Gd',<br>>>>>>>>> pseudo_dir = './'<br>>>>>>>>> outdir='./',<br>>>>>>>>> /<br>
>>>>>>>> &system<br>>>>>>>>> ibrav= 4, celldm(1)= 6.96, celldm(3)= 1.59,<br>>>>>>>>> nat= 2, ntyp=1,<br>>>>>>>>> nspin = 2,<br>
>>>>>>>> starting_magnetization(1)=1.0,<br>>>>>>>>> ecutwfc=55.0,<br>>>>>>>>> ecutrho=220.0,<br>>>>>>>>> occupations ='smearing',<br>
>>>>>>>> smearing ='gauss',<br>>>>>>>>> degauss = 0.01,<br>>>>>>>>> /<br>>>>>>>>> &electrons<br>
>>>>>>>> diagonalization='david',<br>>>>>>>>> mixing_beta = 0.3,<br>>>>>>>>> conv_thr = 1.0d-8,<br>>>>>>>>> /<br>
>>>>>>>> ATOMIC_SPECIES<br>>>>>>>>> Gd 1.0 Gd.GGA-PBE-paw.UPF<br>>>>>>>>> ATOMIC_POSITIONS {crystal}<br>>>>>>>>> Gd 0.33333333 0.66666667 0.25<br>
>>>>>>>> Gd 0.66666667 0.33333333 0.75<br>>>>>>>>> K_POINTS {automatic}<br>>>>>>>>> 4 4 4 0 0 0<br>>>>>>>>> _______________________________________________<br>
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>>><br>>>> --<br>>>> Regards,<br>>>> MOHNISH,<br>>>> -----------------------------------------------------------------<br>>>> Mohnish Pandey,<br>>>> PhD Student,<br>
>>> Center for Atomic Scale Materials Design,<br>>>> Department of Physics,<br>>>> Technical University of Denmark<br>>>> -----------------------------------------------------------------<br>
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