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S a e Ki o Modeling a GaAs-Si in e ace
wi h Quan um Esp esso
A.Ma í and I. A acho
Ins i u o de Ene gía Sola – Uni e sidad Poli écnica de Mad id, Spain
The mo i a ion behind his upload o Zenodo is o p o ide he in e es ed isi o wi h an ini ial se o iles (“s a e
ki ”) so hey can model, isualize and pe haps, e en ca y ou u he esea ch on he physical and elec onic
p ope ies o GaAs/Si in e aces. Behind his bundle is he idea o gaining p og essi e insigh in o he po en ial
g ow h o III-Vs on silicon by echniques such as molecula beam epi axy (MBE): how a oms ea ange, how de-
ec s o igina e, e c. To his end we p o ide:
• The necessa y inpu iles o be execu ed in Quan um Esp esso (see No es below). These a e lis ed in
Table I, showing also how hey can be execu ed oge he wi h some commen s and illus a i e esul s. Fo
he calcula ions we ha e used 12 co es (indica ed by he use o “mpi un -np 12”). This can be omi ed o
single co e calcula ions. In ou case, using a Leno o ThinkPad 21KVS0DM00 Lap op, calcula ion imes
ha e been a ound 2 days o he examples p o ided.
• The Blende ile (GaAs_on_Si.blend wi hin he olde blende ) ha allows isualizing in 3D he a omic
posi ions used in he calcula ions (Fig. 3) as well as au oma ically c ea ing a ideo o isualize he elaxa-
ion o he a oms om hei ini ial posi ions o hei inal posi ions. By using his ile, he eade can isualize
he elaxa ion om di e en isual pe spec i es on hei own. Se e al examples o he ideos ha can be
c ea ed a e included in his bundle as examples: bo om.mk , la e al.mk and on .mk . The Blende ile
includes a sc ip in Py hon whe e he a omic posi ions should be inse ed in o de o au oma ically gene a e
new ideos. Fo inse ing he ini ial a omic posi ions, please sea ch in o he sc ip o he block commen ed
as : # Pa ame e s: Ini ial posi ions o he a oms a e inse ed he e; These posi ions a e inse ed in ame 1
o he ideo. Fo inse ing he inal posi ions, please sea ch o he lines commen ed as # Inse he e he
inal a omic posi ions ob ained a e elaxa ion. These posi ions will be inse ed in ame 250 and Blende
will in e pola e in-be ween. Once he Blende composi ion is c ea ed a e unning he sc ip , he eade is
assumed o ha e some knowledge abou Blende o c ea e hei own ideos wi h he pe spec i e hey
wish. I is also possible o change he colo , size o he a oms, e c. We ecommend his is done in he
py hon sc ip p o ided wi hin Blende . I you c ea e you own ideo, no e you migh need o change he
loca ion whe e he c ea ed ideo ile is s o ed (in ou case, in a mp olde ). Use EEVEE (ins ead o Cycles)
o as e ende ing.
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Table I. P oposed ile empla es in he s a e ki . I is ecommended ha iles a e execu ed in he o de he iles
a e p o ided since some iles equi e he ou pu gene a ed by he p e ious ones.
Name o he ile
Execu ion
Commen s
elax.in
mpi un -np 12 pw.x <
elax.in > elax.ou
Once execu ed, by he end o he ile “ elax.ou ”, look o
he elaxed posi ions o he Ga, As and Si a oms. No e:
“ elax.in” only elaxes he a omic posi ions due o he in-
s uc ion “ elax” wi hin he ile. A mo e accu a e calcula ion
can be done using “ c- elax” ins ead a he cos o a highe
compu a ional ime. The use o “ elax” ne e heless is su -
icien o g asp he gene al idea abou how a oms y o
ind mo e a o able ene ge ic posi ions. This isualiza ion
is a o ed by he use o Blende (see la e ).
sc .in
mpi un -np 12 pw.x <
sc .in > sc .ou
“Sel -consis en - ield” calcula ion. Fo he i s un, we ec-
ommend you inse you sel , in he “sc .in” ile, he elaxed
a omic posi ions ob ained in he “ elax.ou ” ile and s a
he calcula ions “ om_sc a ch”. This migh no be neces-
sa y i you use he “ es a ” op ion ins ead, bu we ha e
no es ed his op ion. In any case, please, ecall ha i you
need o s op he calcula ions in a con olled way, you need
o c ea e he co esponding emp y “.EXIT” ile
(“GaAs_on_Si.EXIT” in ou case i you ha e no changed
ou names o he iles) a any ime in he “ mp” olde and
use he op ion “ es a ”.
nsc .in
mpi un -np 12 pw.x <
nsc .in > nsc .ou
Inc eases he numbe o k poin s calcula ed using he e-
sul s calcula ed in he p e ious sc s ep.
bands.in
mpi un -np 12 pw.x <
bands.in > bands.ou
Calcula es he band diag am.
bands_pos .in
mpi un -np 12
bands.x <
bands_pos .in >
bands_pos .ou
C ea es he iles o plo ing he band diag am. No gap is
expec ed o his s uc u e.
bands.gnuplo
gnuplo
bands.gnuplo
A empla e o plo ing he band diag am o he s uc u e
using he ou pu ile c ea ed by “bands_pos .in”. In one o
i s lines, “bands.gnuplo ” includes he posi ion o he Fe mi
le el ha can be ound in he ile “nsc .ou ” by sea ching
o “Fe mi”. This posi ion will a y depending on he e-
sea ch you ca y ou . Resul is shown in Fig. 1.
dos.in
mpi un -np 12 dos.x <
dos.in > dos.ou
Calcula es he densi y o s a es. Gi es an idea o he en-
e gies o he de ec o ma ion a he in e ace e en when
a oms accommoda e o new posi ions elas ically.
dos.gnuplo
gnuplo dos.gnuplo
Templa e o plo he densi y o s a es ob ained by unning
“dos.in”. Resul s a e shown in Fig. 02.
As_ONCV_PBE-1.2.up
Ga_ONCV_PBE-1.2.up
Ga_ONCV_PBE-1.2.up
Pseudopo en ials o As, Ga and Si. To be included in he
olde “pseudo”.
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Fig. 1. Ene gy band calcula ed wi h Quan um Esp esso o he GaAs/Si in e ace ([001] di ec ion) wi h he iles
p o ided in his “s a e ki ”.
Fig. 2. Densi y o s a es calcula ed wi h Quan um Esp esso o he GaAs/InAs in e ace wi h he iles p o ided in
his “s a e ki ”.
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Fig. 3. Rende ing by Blende o he a omic posi ions used in he simula ion: yellow, silicon a oms; da k g ey, As
a oms; ligh g ay, Ga a oms.
NOTES:
• Quan um Esp esso [1], [2] is an open-sou ce sui e o codes o elec onic-s uc u e calcula ions and ma-
e ials modeling a he nanoscale, based on densi y unc ional heo y, plane wa es, and pseudopo en ials.
I can be downloaded om www.quan um-esp esso.o g oge he wi h he ins uc ions o ins alling i .
Quan um Esp esso can be ins alled bo h in Windows as in Linux. The example we p o ide has been
es ed on Quan um Esp esso 7.3.1 ins alled unde Ubun u 22.04.5 LTS and es ed in a Leno o ThinkPad
21KVS0DM00 Lap op.
• The inpu iles p o ided con ain se e al ins uc ions, bu we make no aim in his documen o explain wha
each ins uc ion does since he eade can easily ind his in o ma ion in he Quan um Esp esso manual
o , nowadays, hey can simply ask AI ools such as Cha GPT (h ps://openai.com/es-ES/cha gp /o e -
iew/) o ob ain a e y good summa y o wha hese ins uc ions do adap ed o hei needs. Cha GPT has
assis ed us in c ea ing he sc ip o he Blende ile and he inpu iles o Quan um Esp esso. Howe e ,
we ha e no used Cha GPT o e iew his ex .
• The ou pu iles ha e no been included o sa e space. They will be c ea ed again once you un he inpu
iles.
• The uni supe cell we use, ex ends 50 A in he z di ec ion o simula e only one mixed laye o GaAs and
Si a oms:
CELL_PARAMETERS angs om
5.43 0.00 0.00
0.00 5.43 0.00
0.00 0.00 50.00
The alue o 5.43 A co esponds o he la ice cons an o silicon since in ou simula ion we wan ed o
pu he Ga and As a oms as i ini ially hey we e also loca ed p ese ing his la ice cons an . GaAs has
a la ge la ice cons an (5.65 A) and, in ac , he simula ion (bes app ecia ed in he ideos) e eals an
expansion o he posi ion o he a oms as expec ed om he di e ence in he alue be ween he wo
la ice cons an s.
• The pseudopo en ials o As, Ga and Si ha e been downloaded om h p://www.quan um-simula-
ion.o g/po en ials/sg15_onc /up / . They a e included wi hin he olde “pseudo”.
• The c ys al s uc u e o Si and GaAs ha e been ob ained om Wikipedia.
• Fo plo ing he ac ual band diag ams, we shall assume “gnuplo ” (www.gnuplo .in o/) is ins alled in you
sys em.
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• Blende can be downloaded om h ps://www.blende .o g/download/
• Files p o ided mus be unde s ood, as men ioned, as s a e ki s o ini ia e esea ch on he elec onic
p ope ies o he GaAs/Si in e ace using Quan um Esp esso. No igo ous physical signi icance o he
esul s he e p esen ed is claimed a his s age. Resul s a e only illus a i e. We hink u he wo k should
con inue by, o example: a) enla ging he supe cell; b) ca ying ou cell elaxa ion (using c- elax); c)
explo ing o he c ys al o ien a ions.
• Some imes, he ollowing e o is gene a ed: “The ollowing loa ing-poin excep ions a e signaling:
IEEE_DENORMAL”. This e o is conside ed non-c i ical and has been igno ed.
Re e ences:
[1] P. Giannozzi e al., “QUANTUM ESPRESSO: a modula and open-sou ce so wa e p ojec o
quan um simula ions o ma e ials,” J. Phys. Condens. Ma e , ol. 21, no. 39, p. 395502, 2009, doi:
10.1088/0953-8984/21/39/395502.
[2] P. Giannozzi e al., “Ad anced capabili ies o ma e ials modelling wi h Quan um ESPRESSO,” J.
Phys. Condens. Ma e , ol. 29, no. 46, p. 465901, 2017, doi: 10.1088/1361-648X/aa8 79.
Acknowledgmen s:
This ac ion has been unded om g an PID2021-124193OB-
C21 (PVBoos e P ojec ) unded by
Spanish Minis e io de
Ciencia e Inno ación wi h Eu opean Funds.
This ac ion has been inanced h ough he R+D ac i i ies p og am wi h e e ence TEC-
2024/ECO-72 and ac onym 4EVERPV-CM g an ed by he Communi y o Mad id h ough
he Gene al Di ec o a e o Resea ch and Technological Inno a ion h ough O de
3177/2024.
