@Book{donohue74:elements,
author = {Jerry Donohue},
title = {The Structures of the Elements},
publisher = {John Wiley \& Sons},
year = 1974,
address ={New York}}
He's a little out of date for some elements, e.g. Boron.
The American Mineralogist Crystal Structure Da
On 10/04/2011 05:43 AM, Ashish Kumar wrote:
> Hello to all,
>
> I have tried for the vc-relax of Mo2C hexagonal system, job is not done
> properly it come out in between and the atomic positions
>
> what I have given in the input file and what I am getting in the out
> file is different.
> (i) Why
For more detail on many other physically plausible equations of state, see:
@Book{anderson95:eos,
author = {Orson L. Anderson},
title ={Equations of State of Solids for Geophysical and
Ceramic Science},
publisher ={Oxford University Press},
year = 1995,
nu
Since BCC Fe is magnetic, I suspect you will get better results by adding
nspin=2,
to your &system block.
On 12/05/2011 04:13 AM, Lily Anh wrote:
> Hi all,
>
> I am running a 'vc-md' calculation with PW.X in QE v4.1.1. The system is
> bcc-Fe supercell of 16 atoms. The target temperature wer
Dayrl,
Looking at your output, it seems that you are very far from the minimum
energy beta-Sn structure:
entering subroutine stress ...
total stress (Ry/bohr**3) (kbar) P=
42.95
0.00079257 0. 0. 116.59 0.00 0.00
0.
Not quite:
celldm(1) =11.15433936, celldm(3) =0.54170527
On 10/08/2010 03:55 PM, Daryl Chrzan wrote:
> Michael,
>
> Thank you for the response. I agree that I am far from the minimum.
> However, when I do get to the minimum, I end up with a c/a ratio that is far
> off, and an energy differ
Two things:
First,
Having atoms designated Mn1 and Mn2 reduces the symmetry from Fm(3-)m
(cubic rocksalt) to R(-3)m (rhombohedral), which is why you see a
rhombohedral lattice in the output for the rocksalt structure.
Second,
What answer do you get when you use the primitive cell for the Rock
Sorry, I missed the AFM part. In your case, then, the system is
rhombohedral, and will relax away from the cubic structure, as your
results showed.
On 01/20/2011 01:08 AM, mohnish pandey wrote:
> Dear Michael!
> To get an AFM ground state we I think we
> should have at
If the B1 structure is unstable with respect to the B2 structure above
130 GPa, but the B2 structure is dynamically unstable at and above 130
GPa, there are two possible conclusions:
1) The phonons for the B2 structure were not calculated accurately, or
2) There is a competing structure that is
rectly because the convergence is good with
> higher k points
> second is that i have tested zns,wc,NiAs phase none of them have less
> enthalpy at 130 gpa
> other thing is that it is stable at above 250 gpa
>
>
> On Wed, Aug 24, 2011 at 7:38 PM, Mike Mehl <mailto:Michael.Mehl
> anaharmonic contributions
> or it may be due to band closing phenomenon
> can u explain this more correctly because i am doing calculation on
> transition metal carbides
> On Wed, Aug 24, 2011 at 9:01 PM, Mike Mehl <mailto:Michael.Mehl at nrl.navy.mil>> wrote:
&g
Apologies if this goes through twice, the first time I used the wrong
email address and I don't know if the moderator will pass the message on
or not:
Attached, if I did things correctly, are two input files. Both of them
are used to do an scf calculation for a frozen phonon determination of
fr
I've been doing frozen phonon calculations with pwscf, and found a
difference in the output of the code based on how I ordered the list of
atomic positions.
Specifically:
Both of the attached runs compute the energy of an 8 atom supercell of
IrV in the L1_0 structure with no displacements away
Ah. A glitch in the computer architecture, then. Thanks Paolo.
On 04/17/2010 08:37 AM, Paolo Giannozzi wrote:
> This is what I got on a sp6 (FFT grids are slghtly different, the rest
> should be
> the same; I used the most recent version). The final steps of
> self-consistency
> are slightly di
If you know the space group of your system (for the diamond structure
it's 227), you can find all the high symmetry points at
http://www.cryst.ehu.es/cryst/get_kvec.html
along with a labeled picture of the first Brillouin zone.
On 04/28/2011 12:33 PM, Eduardo Ariel Menendez Proupin wrote:
> Hi
To follow up on Nicola's point, the bulk modulus of sapphire is 240 GPa or
2400 kbar (http://www.mt-berlin.com/frames_cryst/descriptions/sapphire.htm).
So a 1 kbar error corresponds to a very small change in volume.
If we use the quick and dirty Birch equation of state:
P(V) = 3/2 K0 [ (V0/V)^(7
All right, the fourth time is a charm:
The full tetragonal unit cell of beta-tin has four atoms in it.
However, the primitive body-centered unit cell as two atoms in it.
You may want to look up the beta-tin structure, e.g.
http://cst-www.nrl.navy.mil/lattice/struk/a5.html
and see how you can c
Again, look up the difference between
1) the tetragonal lattice
and
2) the body-centered tetragonal lattice
Until you understand that, you will not understand your problem.
On 01/04/2012 10:28 AM, bhabya sahoo wrote:
> i give the input as bct containing
> two atoms having position
> 0, 0, 0
>
We've changed the link slightly. It's now:
http://cst-www.nrl.navy.mil/users/mehl/papers/cij453.pdf
On 09/21/2010 08:44 AM, Eyvaz Isaev wrote:
>
>
> *From:* mohsen modaresi
> See papers: Mehl et al., PhysRev.B 41, 10311,
If you found a phonon with an imaginary frequency, then you can find a
supercell of the L10 structure, displace the atoms in it according to
the symmetry of the phonon, and relax the structure to obtain another
structure with lower energy (enthalpy if you are working at fixed
pressure). Here's
On 05/19/2010 08:11 AM, partha sarathi ghosh wrote:
> Dear all,
> I am trying to do phonon calculation of bcc-Zr from
> (0,0,0) to (1,1,1) in q-space.But I am getting negative frequencies in
> several q-points, also my curve is very different from experimental one.
> I optimized the s
Dear Ghosh,
If I've read the paper correctly, the paper you are looking at is
entirely computational, not experimental, so basically you are trying to
decide if pseudopotentials used in that paper and in your calculation
are going to give the same result. You're not comparing with
experiment,
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