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<body class='hmmessage'><div dir='ltr'>Dear all,<br><br>I studied the total energy variation versus volume of
the GaN and GaBi cristals, in both Zinc-blenbe au wurtzite structure. my
calculation demonstrates that for the GaBi material the Zinc-blende
structure is the must stable, while the wurtzite is the fundamental
structure for the GaN material which is in great agreement whith the
experimental results. Aiming the determination of the phase <span id="ecxresult_box" class="ecxshort_text" lang="en"><span class="ecxhps">concentration</span></span>
variation, I also investigated the total energy variation of the GaNBi
alloys for different concentration of the Bi element for both noted
structures. During on calculation we were waiting for a phase transition
from wurtzite to Zinc-blende structures follwing the Bi concentration
increase, which is not confirmed by our main calculation fact:<br>We found that in fast step phase transition was from wurtzite to zinc-blende, then retured to wurtzite then to Zinc-blende <span id="ecxresult_box" class="ecxshort_text" lang="en"><span class="ecxhps">increasing the concentration</span> <span class="ecxhps">of</span> <span class="ecxhps">Bi</span><span>.</span></span><span id="ecxresult_box" lang="en"><span class="ecxhps"></span></span> <br>My input is below:<br><font style="font-size:20pt;" size="5"> </font><font style="font-size:20pt;" size="5" color="#8C0095">Zinc-blende structutre:</font><br><br>&control<br> calculation='relax'<br> restart_mode='from_scratch',<br> tstress = .true.<br> tprnfor = .true.<br> prefix='810-28',<br> pseudo_dir = '/home/projet/pseudo/',<br> outdir='/home/projet/tp/'<br> /<br> &system<br> ibrav= 1, celldm(1) =9.00, nat= 8, ntyp= 3,<br> ecutwfc =50.0, ecutrho = 200.0,<br> /<br> &electrons<br> diagonalization='david'<br> conv_thr = 1.0e-6<br> mixing_beta = 0.6<br> /<br> &ions<br> ion_dynamics='bfgs'<br> /<br>ATOMIC_SPECIES<br> Ga 69.726 Ga.pz-bhs.UPF<br> n 14.0067 n_pz.upf<br> bi 208.980 bi_pz.upf<br>ATOMIC_POSITIONS (crystal)<br>Ga 0.00000000 0.00000000 0.00000000<br>Ga 0.50000000 0.50000000 0.00000000<br>Ga 0.50000000 0.00000000 0.50000000<br>Ga 0.00000000 0.50000000 0.50000000<br>bi 0.25000000 0.25000000 0.25000000<br>bi 0.75000000 0.75000000 0.25000000<br>n 0.75000000 0.25000000 0.75000000<br>n 0.25000000 0.75000000 0.75000000<br>K_POINTS (automatic)<br> 5 5 5 1 1 1<br><br><font style="font-size:20pt;" size="5"> </font><font style="font-size:20pt;" size="5" color="#8C0095">Wurtzite structutre:</font><br><br>&control<br> calculation='relax'<br> restart_mode='from_scratch',<br> tstress = .true.<br> tprnfor = .true.<br> prefix='5750-28',<br> pseudo_dir = '/home/projet/pseudo/',<br> outdir='/home/projet/tp/'<br> /<br> &system<br> ibrav= 4, celldm(1) =6.10, celldm(3) =3.28, nat= 8, ntyp= 3,<br> ecutwfc =50.0, ecutrho = 200.0,<br> /<br> &electrons<br> diagonalization='david'<br> conv_thr = 1.0e-6<br> mixing_beta = 0.4<br>/<br> &ions<br> ion_dynamics='bfgs'<br> /<br>ATOMIC_SPECIES<br>
Ga 69.726 Ga.pz-bhs.UPF<br>
n 14.0067 n_pz.upf<br>
bi 208.980 bi_pz.upf<br>ATOMIC_POSITIONS (crystal)<br>Ga 0.00000000 0.00000000 0.00000000<br>Ga 0.33333333 0.66666667 0.23787476<br>Ga 0.00000000 0.00000000 0.47574952<br>Ga 0.33333333 0.66666667 0.71362428<br>bi 0.00000000 0.00000000 0.17840607<br>bi 0.33333333 0.66666667 0.41628083<br>n 0.00000000 0.00000000 0.65415559<br>n 0.33333333 0.66666667 0.89203034<br>K_POINTS (automatic)<br> 6 6 2 1 1 1<br><br>Could you please give me some suggestions?<br>Thank you in advance.<br><br>ALAYA Ramzi </div></body>
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