<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear Chris,<div class=""><br class=""></div><div class="">I do not know what the origin of your problem may be. What I can say is that it is probably not a good idea to run such a relatively large computation just to evaluate the vibrational properties of a thin metal layer. A smarter approach would probably be to compute interatomic force constants using a thinner slab (the range of the force constants is likely 2-3 bond lengths in Cu), and than to use the ab initio force constant to build a model for a slab of any thickness … By the way the size of the vacuum region is likely also an overkill …</div><div class=""><br class=""></div><div class="">SB</div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 6 Nov 2018, at 14:31, Christoph Wolf <<a href="mailto:wolf.christoph@qns.science" class="">wolf.christoph@qns.science</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Dear all,<div class=""><br class=""></div><div class="">I am trying to calculate the phonon spectrum for a series of thin metal layer. However there seem to be a few "pathological" cases such as Cu(111) where, no matter what, I cannot achieve convergence during the ph.x calculation.</div><div class=""><br class=""></div><div class="">I have tried, to no avail, change mixing parameter, k point sampling, ecutrho, ecutwfc, smearing type, occupation type, ...</div><div class=""><br class=""></div><div class="">If someone has a hint on how to tackle this I would be entirely grateful. I know it can be done as there are a few works out there focusing on thin metal film phonons but non of them has additional information.</div><div class=""><br class=""></div><div class="">The general setup is 11 layers of metal padded by 20A of vacuum. I generated the layers using "thermo_pw" and I manually and meticulously checked bond lengths and residual forces on the atoms after relaxation (<1e-6). </div><div class=""><br class=""></div><div class="">Any help is very welcome!</div><div class=""><br class=""></div><div class="">Thanks in advance and with best regards,</div><div class="">Chris <br clear="all" class=""><div class=""><br class=""></div>-- <br class=""><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class="">Postdoctoral Researcher<br class="">Center for Quantum Nanoscience, Institute for Basic Science<br class="">Ewha Womans University, Seoul, South Korea<blockquote type="cite" style="font-size:12.8px" class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""></div></div></div></blockquote></div></div></div></div>
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<span class="Apple-style-span" style="border-collapse: separate; font-variant-ligatures: normal; font-variant-position: normal; font-variant-numeric: normal; font-variant-alternates: normal; font-variant-east-asian: normal; line-height: normal; orphans: 2; text-indent: 0px; widows: 2; border-spacing: 0px;"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><span class="Apple-style-span" style="border-collapse: separate; font-variant-ligatures: normal; font-variant-position: normal; font-variant-numeric: normal; font-variant-alternates: normal; font-variant-east-asian: normal; line-height: normal; orphans: 2; text-indent: 0px; widows: 2; border-spacing: 0px;"><span class="Apple-style-span" style="border-collapse: separate; font-variant-ligatures: normal; font-variant-position: normal; font-variant-numeric: normal; font-variant-alternates: normal; font-variant-east-asian: normal; line-height: normal; orphans: 2; text-indent: 0px; widows: 2; border-spacing: 0px;"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><span style="font-size: 12px;" class="">— </span></div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div style="margin: 0px;" class=""><font class="Apple-style-span"><span style="font-size: 12px;" class="">Stefano Baroni - Trieste — </span><a href="http://stefano.baroni.me" style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-stroke-width: 0px;" class="">http://stefano.baroni.me</a><span style="font-size: 12px;" class=""> </span></font></div></div><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-stroke-width: 0px;" class=""><br class=""></div></div></div></div></div></div></div></span></span></div></div></div></span><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">
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