[Pw_forum] Atomic positions for Black Phosphorus calculations
Duc-Long NGUYEN
longnguyenqtr at gmail.com
Tue Jan 12 00:38:04 CET 2016
Dear Elio,
ATOMIC_POSITIONS crystal
P -0.89832 0.89832 0.91944
P -0.39832 0.39832 0.58056
_P -0.10168 0.10168 0.08056_
P 0.10168 0.89832 0.91944
_P -0.10168 1.10168 0.08056_
P -0.60168 0.60168 0.41944
P -0.39832 1.39832 0.58056
P 0.39832 0.60168 0.41944
These two atom positions have the same coordinate. This could be the
problem.
Duc-Long
On 1/12/2016 6:44 AM, Elio Physics wrote:
>
> Dear all,
>
>
> I am trying to perform some calculations on Black Phosphorus (BP). To
> get the atomic positions I used the Crystal Builder, where I have
> chosen the lattice type to be base centered orthorhombic. The
> "builder" produced a set of cartesian and fractional (in terms of the
> primitive cell vectors) . I have used the fractional ones and I have
> also used ibrav=0 with the CELL_PARAMETERS defined as in the builder
> (a/2, -b/2, 0), (a/2, b/2,0), (0,0,c). However I have got the
> following error:
>
>
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> from check_atoms : error # 1
> atoms # 1 and # 4 overlap!
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>
> Doing the same calculation with ibrav=8 and using the coordinates
> produced by the Crystal builder for a simple orthorhombic does not
> produce any errors. Can anyone please tell me what is wrong with atoms
> (1) and (4). Is BP simple or base centered orthorhombic..Where can I
> find the coorect atomic position of bulk BP? The scf input is below:
>
>
> &CONTROL
> prefix='bp',
> calculation='scf',
> restart_mode='from_scratch',
> wf_collect=.true.,
> forc_conv_thr=1.D-4
> etot_conv_thr=1.D-5
> tstress=.true.,
> tprnfor=.true.,
> pseudo_dir ='/home_cluster/fis718/elio/espresso-4.1.3/pseudo',
> outdir='/home_cluster/fis718/elio/espresso-4.1.3/BP/OUT'
> /
> &SYSTEM
> ibrav=0,celldm(1)=6.26179,nat=8, ntyp= 1, ecutwfc=10, ecutrho=40,
> occupations='smearing', london=.true., smearing='mp',
> degauss=0.035,nbnd=32
> /
> &ELECTRONS
> conv_thr=1.D-8,
> mixing_beta=0.1
> /
> &IONS
> ion_dynamics='bfgs'
> /
> &CELL
> cell_dynamics='bfgs'
> press=0.0
> /
> ATOMIC_SPECIES
> P 30.97376 P.pbe-n-van.UPF
> ATOMIC_POSITIONS crystal
> P -0.89832 0.89832 0.91944
> P -0.39832 0.39832 0.58056
> P -0.10168 0.10168 0.08056
> P 0.10168 0.89832 0.91944
> P -0.10168 1.10168 0.08056
> P -0.60168 0.60168 0.41944
> P -0.39832 1.39832 0.58056
> P 0.39832 0.60168 0.41944
>
> K_POINTS automatic
> 2 2 2 0 0 0
>
> CELL_PARAMETERS alat
> 0.5000 -1.58106 0.0000
> 0.500 1.58106 0.0000
> 0.0000 0.00000 4.3763
>
>
> thanks
>
> Elio Arbid
> University of Nottingham
> UK
>
>
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> http://pwscf.org/mailman/listinfo/pw_forum
--
Duc-Long Nguyen
Graduate Student, Molecular Science and Technology Program, TIGP
Institute of Atomic and Molecular Sciences,
Academia Sinica, Taipei 106, Taiwan
Phone +886 979279073
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