<div dir="ltr">The Bravais lattice for the case of unique axis 'b' should be the one corresponding to case ibrav=-13, as described in the documentation<br><div><br></div><div>Paolo<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Dec 15, 2020 at 9:30 AM 连云龙 <<a href="mailto:lianyl@ihep.ac.cn">lianyl@ihep.ac.cn</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><p>
Dear QE experts,
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I find it confusing in the description Wyckoff position specifications in the card ATOMIC_POSITIONS.
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<a href="https://www.quantum-espresso.org/Doc/INPUT_PW.html" target="_blank">https://www.quantum-espresso.org/Doc/INPUT_PW.html</a>
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For space group No.12 under the convention unique axis b, there are three cell choices. The Wyckoff position 4i has different forms for the three choices, namely (according to ITA)
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UNIQUE AXIS b, CELL CHOICE 1
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4i <span style="white-space:normal"><span style="white-space:normal">x,0,z ; </span><span style="white-space:normal">x+1/2,1/2,z ; <span style="white-space:normal">xb,0,zb ; </span><span style="white-space:normal">xb+1/2,1/2,zb</span><span style="white-space:normal"></span></span><span style="white-space:normal"></span></span>
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<span style="white-space:normal"><span style="white-space:normal">
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UNIQUE AXIS b, CELL CHOICE 2
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4i x,0,z ; x,1/2,z<span style="white-space:normal">+1/2</span> ; xb,0,zb ; xb,1/2,zb<span style="white-space:normal">+1/2</span>
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UNIQUE AXIS b, CELL CHOICE 3
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4i x,0,z ; x<span style="white-space:normal">+1/2</span>,1/2,z+1/2 ; xb,0,zb ; xb<span style="white-space:normal">+1/2</span>,1/2,zb+1/2
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(xb means x-bar)
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If I am to write the <span style="white-space:normal">ATOMIC_POSITIONS</span> card, how should I specify the parameters x and z? How do I know that pw.x takes <span style="white-space:normal">CELL CHOICE 1/2/3 ?</span>
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<span style="white-space:normal"><span style="white-space:normal"><br>
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<span style="white-space:normal"><span style="white-space:normal">Thank you for your help.</span></span>
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<span style="white-space:normal"><span style="white-space:normal"><br>
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<span style="white-space:normal"><span style="white-space:normal">Best regards,</span></span>
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<span style="white-space:normal"><span style="white-space:normal">Yunlong Lian</span></span>
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<span>--<br>
Yunlong LIAN
ORCID : <a href="https://orcid.org/0000-0002-9474-2181" target="_blank">https://orcid.org/0000-0002-9474-2181</a>
CSNS, Dongguan Neutron Science Center
Dongguan, Guangdong, P. R. China
连云龙
中国散裂中子源 中子科学部
A1-629 (内线 303)
中国广东省东莞市</span><br>
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