Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
Thank you again for the detailed explanation. I have some comments to make Every one knows that the magnetic ordering of the NaCl structure of NiO is paramagnetic, while that of the rhombohedral structure is antiferromagnetic. But, my question is about if we have no information about the material. We have to study the magnetic nature of the material under different crystal structures. Thank you again -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
Both structures are almost the same, the rhombohedral one is shortened or elongated in the 111 direction If the cell is shortened then the Ni-Ni distance in the 111 planes is larger than the distance between planes, then there is an antiferromagnetic ordering, with Ni up in one plane and Ni dn in the next. The cubic FCC has frustration, which leads to non-magnetic ordering or as you say stays paramagnetic. Thank you again for the detailed explanation. I have some comments to make Every one knows that the magnetic ordering of the NaCl structure of NiO is paramagnetic, while that of the rhombohedral structure is antiferromagnetic. But, my question is about if we have no information about the material. We have to study the magnetic nature of the material under different crystal structures. Thank you again -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
This problem is quite interesting; You have Ni in a FCC arrangement, so you have Ni tetrahedra, so how can you place them in an antiferromangnetic order??? It is frustratng!!! Well this is known as geometric frustration, which is a very interesting field!!! On the opposite stance immagine a simple Ni crystal with an antiferromagnetic order, there is a simple answer; alternating spins in the axis, like the NaCl crystal: Na represents up, Cl dn; Now, the picture that you sent the crystal has Ni atoms alternating in spin in the 111 planes; one plane up, next dn. In each plane the Ni are ordered ferromagnetic!!! This is not the correct structure, but it is good for a approximate calculation. To reproduce this structure you start by defining the structure as shown in your picture; You make a crystal with 2 atoms, cubic F with Na at 0,0,0 and O at 1/2,0,0. The conventional structure looks like the one that you sent, but the primitive one is simpler. The problem is that when you try to put one Ni plane up and the next dn then the Ni at 000 is up and the one at 111 is dn, then you have to double the structure in the 111 direction: You make the cell with a=b=c=4.17A, alfa=beta=gamma=89.999 (not 90, but close) and put Ni 000 0,1/2,1/2 1/2,0,1/21/2,1/2,0 O 1/2,0,0 0,1/2,00,0,1/21/2,1/2,1/2 with sgroup it will convert it to rhombohedral which with supercell you can now convert it hexagonal and you can expand in the 001 direction (wich in the original cell was 111) De: wien-boun...@zeus.theochem.tuwien.ac.at wien-boun...@zeus.theochem.tuwien.ac.at en nombre de Abed Reg jazai...@gmail.com Enviado: domingo, 30 de noviembre de 2014 04:05 p.m. Para: wien@zeus.theochem.tuwien.ac.at Asunto: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation Hello again How to reproduce this structure of NiO if we consider the two atoms of Ni (up and dn ) as inequivalent. Here is the structure NiO structurehttp://4.bp.blogspot.com/-EzItbno5RvU/VHi-n_0yT5I/AJk/Hyf7Qhg_3ao/s1600/Antiferro-NiO.png -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
Thank you Mr Delamora for your reply First, we can create the structure of Cr with 2 ways: 1- with one atom and bcc lattice (0,0,0) or 2- with two atoms and P lattice (0,0,0) and (.5,.5,.5) But the second way allows us to do the antiferromagnetic calculation by flipping the spins of one atom. Sceond, the same thing, normally, for the Ni element. We can prodce the structure with 2 ways: 1- with one atom and fcc lattice (0,0,0) or 2- with four atoms and P lattice (0,0,0) (1/2,1/2,0) (0,1/2,1/2) (1/2,0,1/2) Here we can flip the spins of the two atoms of Ni to do the antiferromagnetic calculation. Third, i want to do the same thing with the NaCl structure (NiO) . I have to get two atoms of Ni at least to reproduce te same crystal structure. And starting with this structure i will determine the equilibrium parameters. the question still how to reproduce the NaCl structure with two or four atoms of Ni so we can do antiferromagnetic calculation with this structure. -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
Here I make the structures step by step *** Here you have; aaa.struct-cub-F with supercell = aaa.struct-cub-P change angles aaa.struct-89.999 with initialize calc and x sgroup = aaa.struct-rho with supercell = aaa.struct-hex with supercell = aaa.struct-hex-2 here the Ni at c=0, 1/3 and 2/3 are marked as Ni 1 c=1/6, 3/6 and 5/6 are marked as Ni 2 with initialize calc and x sgroup = aaa.struct-anti Which is the structure that you want. ** In this aaa.struct-anti with F4 you see the hexagonal structure where you see the Ni-1 planes and Ni-2 planes while with F3 you see the primitive cell. De: wien-boun...@zeus.theochem.tuwien.ac.at wien-boun...@zeus.theochem.tuwien.ac.at en nombre de delamora delam...@unam.mx Enviado: domingo, 30 de noviembre de 2014 04:51 p.m. Para: wien@zeus.theochem.tuwien.ac.at Asunto: Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation This problem is quite interesting; You have Ni in a FCC arrangement, so you have Ni tetrahedra, so how can you place them in an antiferromangnetic order??? It is frustratng!!! Well this is known as geometric frustration, which is a very interesting field!!! On the opposite stance immagine a simple Ni crystal with an antiferromagnetic order, there is a simple answer; alternating spins in the axis, like the NaCl crystal: Na represents up, Cl dn; Now, the picture that you sent the crystal has Ni atoms alternating in spin in the 111 planes; one plane up, next dn. In each plane the Ni are ordered ferromagnetic!!! This is not the correct structure, but it is good for a approximate calculation. To reproduce this structure you start by defining the structure as shown in your picture; You make a crystal with 2 atoms, cubic F with Na at 0,0,0 and O at 1/2,0,0. The conventional structure looks like the one that you sent, but the primitive one is simpler. The problem is that when you try to put one Ni plane up and the next dn then the Ni at 000 is up and the one at 111 is dn, then you have to double the structure in the 111 direction: You make the cell with a=b=c=4.17A, alfa=beta=gamma=89.999 (not 90, but close) and put Ni 000 0,1/2,1/2 1/2,0,1/21/2,1/2,0 O 1/2,0,0 0,1/2,00,0,1/21/2,1/2,1/2 with sgroup it will convert it to rhombohedral which with supercell you can now convert it hexagonal and you can expand in the 001 direction (wich in the original cell was 111) De: wien-boun...@zeus.theochem.tuwien.ac.at wien-boun...@zeus.theochem.tuwien.ac.at en nombre de Abed Reg jazai...@gmail.com Enviado: domingo, 30 de noviembre de 2014 04:05 p.m. Para: wien@zeus.theochem.tuwien.ac.at Asunto: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation Hello again How to reproduce this structure of NiO if we consider the two atoms of Ni (up and dn ) as inequivalent. Here is the structure NiO structurehttp://4.bp.blogspot.com/-EzItbno5RvU/VHi-n_0yT5I/AJk/Hyf7Qhg_3ao/s1600/Antiferro-NiO.png -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie aaa.struct-cub-F Description: aaa.struct-cub-F aaa.struct-cub-P Description: aaa.struct-cub-P aaa.struct-89.999 Description: aaa.struct-89.999 aaa.struct-rho Description: aaa.struct-rho aaa.struct-hex Description: aaa.struct-hex aaa.struct-hex-2 Description: aaa.struct-hex-2 aaa.struct-anti Description: aaa.struct-anti ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
You are confused, the Cr structure is B, and you can easily separate the up and dn, while the NiO is F and there you have a clear frustration. In what I have just sent the problem is not as simple. De: wien-boun...@zeus.theochem.tuwien.ac.at wien-boun...@zeus.theochem.tuwien.ac.at en nombre de Abed Reg jazai...@gmail.com Enviado: domingo, 30 de noviembre de 2014 05:53 p.m. Para: wien@zeus.theochem.tuwien.ac.at Asunto: Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation Thank you Mr Delamora for your reply First, we can create the structure of Cr with 2 ways: 1- with one atom and bcc lattice (0,0,0) or 2- with two atoms and P lattice (0,0,0) and (.5,.5,.5) But the second way allows us to do the antiferromagnetic calculation by flipping the spins of one atom. Sceond, the same thing, normally, for the Ni element. We can prodce the structure with 2 ways: 1- with one atom and fcc lattice (0,0,0) or 2- with four atoms and P lattice (0,0,0) (1/2,1/2,0) (0,1/2,1/2) (1/2,0,1/2) Here we can flip the spins of the two atoms of Ni to do the antiferromagnetic calculation. Third, i want to do the same thing with the NaCl structure (NiO) . I have to get two atoms of Ni at least to reproduce te same crystal structure. And starting with this structure i will determine the equilibrium parameters. the question still how to reproduce the NaCl structure with two or four atoms of Ni so we can do antiferromagnetic calculation with this structure. -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] What's the crystal structure of NaCl in antiferromagnetic calculation
Answering your question of NiO with a P lattice; If you take a P structure with 4 Ni and 4 O then you can flip two Ni atoms and you have an antiferro in the 100 direction, which is not the one that you sent in the figure In my earlier message you can see the antiferro ordering in the 111. Both of these structures are frustrated, that is, you cannot put an antiferromagnetic ordering in which the nearest Ni atoms are always antiparallel. First, we can create the structure of Cr with 2 ways: 1- with one atom and bcc lattice (0,0,0) or 2- with two atoms and P lattice (0,0,0) and (.5,.5,.5) But the second way allows us to do the antiferromagnetic calculation by flipping the spins of one atom. Second, the same thing, normally, for the Ni element. We can produce the structure with 2 ways: 1- with one atom and fcc lattice (0,0,0) or 2- with four atoms and P lattice (0,0,0) (1/2,1/2,0) (0,1/2,1/2) (1/2,0,1/2) Here we can flip the spins of the two atoms of Ni to do the antiferromagnetic calculation. Third, i want to do the same thing with the NaCl structure (NiO) . I have to get two atoms of Ni at least to reproduce the same crystal structure. And starting with this structure i will determine the equilibrium parameters. the question still how to reproduce the NaCl structure with two or four atoms of Ni so we can do antiferromagnetic calculation with this structure. *** -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
