<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Thank you Giuseppe for your answer.<div><br></div><div>Best,</div><div>Pascal</div><div><br><div><div>Le 29 juil. 2015 à 23:26, Giuseppe Mattioli <<a href="mailto:giuseppe.mattioli@ism.cnr.it">giuseppe.mattioli@ism.cnr.it</a>> a écrit :</div><br class="Apple-interchange-newline"><blockquote type="cite"><br>Dear Pascal<br>If I remember well, you can obtain the cell dipole trajectory by <br>adding assume_isolated='mp' to your cp.x molecular dynamics input of a <br>system contained in a cubic cell (mp is defined for cubic cells only). <br>But the system should be really "isolated" (e.g., a molecule with its <br>center of mass always near to the center of the box) or you may have <br>jumps in the dipole due to PBC which should result in noise when you <br>FFT the dipole autocorrelation function. In my experience (an isolated <br>Co-oxo cluster), it was the only way to obtain an IR spectrum in a <br>DFT+U framework (DFPT still does not work together with DFT+U). It <br>should be also useful in the case of vdw corrections implemented in <br>cp.x.<br>HTH<br>Giuseppe<br><br>Quoting Pascal Boulet <<a href="mailto:pascal.boulet@univ-amu.fr">pascal.boulet@univ-amu.fr</a>>:<br><br><blockquote type="cite">Thank you Paolo and Nicola for your answer.<br><br>Best<br>Pascal<br><br>Le 29 juil. 2015 à 18:16, Paolo Giannozzi <<a href="mailto:p.giannozzi@gmail.com">p.giannozzi@gmail.com</a>> a écrit :<br><br><blockquote type="cite">From the FFTs of the atomic velocity autocorrelation function you <br>can extract phonon frequencies, but you do not get "true" spectra<br><br>Paolo<br><br>On Wed, Jul 29, 2015 at 6:08 PM, Pascal Boulet <br><<a href="mailto:pascal.boulet@univ-amu.fr">pascal.boulet@univ-amu.fr</a>> wrote:<br>Hello,<br><br>Isn’t it possible to get IR spectra from the FFTs of the atomic <br>velocity autocorrelation function?<br><br>Pascal<br><br>Le 29 juil. 2015 à 17:58, Nicola Marzari <<a href="mailto:nicola.marzari@epfl.ch">nicola.marzari@epfl.ch</a>> a écrit :<br><br><blockquote type="cite"><br>Dear Yin,<br><br><br>you need to calculate at every time step the total dipole in the unit<br>cell, and then do the fourier transform of the autocorrelation - see e.g.<br>here: <a href="http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.81.1235">http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.81.1235</a> or many<br>other papers published on the topic.<br><br>Note that if you do Car-Parrinello MD, rather than Born-Oppenhimer MD,<br>the vibrational frequencies can be slightly softened due to the fact<br>that the ions are dressed (and slowed down) by the coefficients of the<br>plane waves. The smaller the fictitious mass, the small the effect.<br><br>Now, I'm not sure how to write the polarization at every time step -<br>maybe others can comment or add to the documentation. For PWSCF<br>you'd switch on lberry, but I'm not sure if you can do it during an<br>md (if now, maybe switch on lelfield, and then keep the applied field<br>equal to zero).<br><br>In CP I suppose you could switch tefield on, but still have zero<br>applied field.<br><br>Any other suggestion? Also, I think that tefield in CP and in PWSCF<br>mean different things - shall we switch the name in CP to lelfield?<br><br><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span>nicola<br><br><br><br>On 29/07/2015 15:56, <a href="mailto:liyincumt@gmail.com">liyincumt@gmail.com</a> wrote:<br><blockquote type="cite">Dear Quantum Espresso developers,<br><br>I want to obtain IR spectra of crystals at room temperature. Considering<br>the temperature effect, I decided to use CPMD. I wonder whether it is<br>possible to get IR spectra from CPMD trajectory in Quantum Espresso?<br>What's more, can I involve vdw-correction in CPMD? If yes, can IR<br>spectra be calculated in the presence of vdw-correction?<br><br>Thank you very much!<br><br>Best Regards,<br>------------------------------------------------------------------------<br>Dr. Yin Li<br>Department of Biophysics,Medical School, University of Pecs,<br>No.12 Szigeti Street, Pecs, H-7624, HUNGARY<br>Phone: +36-72-535271/36271<br><br><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://pwscf.org/mailman/listinfo/pw_forum<br><br></blockquote><br>--<br>----------------------------------------------------------------------<br>Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL<br>Director, National Centre for Competence in Research NCCR MARVEL, EPFL<br><a href="http://theossrv1.epfl.ch/Main/Contact">http://theossrv1.epfl.ch/Main/Contact</a> <a href="http://nccr-marvel.ch/en/project">http://nccr-marvel.ch/en/project</a><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://pwscf.org/mailman/listinfo/pw_forum<br></blockquote><br>--<br>Pascal Boulet - MCF HDR, Resp. L1 MPCI - DEPARTEMENT CHIMIE<br>Aix-Marseille Université - ST JEROME - Avenue Escadrille Normandie <br>Niemen - 13013 Marseille<br>Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50<br>Site : <a href="http://allos.up.univ-mrs.fr/pascal">http://allos.up.univ-mrs.fr/pascal</a> - Email : <br><a href="mailto:pascal.boulet@univ-amu.fr">pascal.boulet@univ-amu.fr</a><br>Afin de respecter l'environnement, merci de n'imprimer cet email <br>que si nécessaire.<br><br><br>_______________________________________________<br>Pw_forum mailing list<br>Pw_forum@pwscf.org<br>http://pwscf.org/mailman/listinfo/pw_forum<br><br><br><br>--<br>Paolo Giannozzi, Dept. Chemistry&Physics&Environment,<br>Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br>_______________________________________________<br>Pw_forum mailing list<br>Pw_forum@pwscf.org<br>http://pwscf.org/mailman/listinfo/pw_forum<br></blockquote><br>--<br>Pascal Boulet - MCF HDR, Resp. L1 MPCI - DEPARTEMENT CHIMIE<br>Aix-Marseille Université - ST JEROME - Avenue Escadrille Normandie <br>Niemen - 13013 Marseille<br>Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50<br>Site : <a href="http://allos.up.univ-mrs.fr/pascal">http://allos.up.univ-mrs.fr/pascal</a> - Email : <a href="mailto:pascal.boulet@univ-amu.fr">pascal.boulet@univ-amu.fr</a><br>Afin de respecter l'environnement, merci de n'imprimer cet email que <br>si nécessaire.<br></blockquote><br><br>-- <br>********************************************************<br>- Article premier - Les hommes naissent et demeurent<br>libres et ègaux en droits. Les distinctions sociales<br>ne peuvent être fondèes que sur l'utilitè commune<br>- Article 2 - Le but de toute association politique<br>est la conservation des droits naturels et<br>imprescriptibles de l'homme. Ces droits sont la libertè,<br>la propriètè, la sùretè et la rèsistance à l'oppression.<br>********************************************************<br><br> Giuseppe Mattioli<br> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br> v. Salaria Km 29,300 - C.P. 10<br> I 00015 - Monterotondo Stazione (RM)<br> Tel + 39 06 90672836 - Fax +39 06 90672316<br> E-mail: <<a href="mailto:giuseppe.mattioli@ism.cnr.it">giuseppe.mattioli@ism.cnr.it</a>><br><br>_______________________________________________<br>Pw_forum mailing list<br><a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>http://pwscf.org/mailman/listinfo/pw_forum</blockquote></div><br><div>
--<br><div style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Tahoma, Verdana, Arial, Helvetica, sans-serif; font-size: 15px; line-height: 22px;"><span style="color: rgb(34, 187, 234); font-size: 14px; font-family: verdana; font-weight: 700;">Pascal Boulet</span> <span style="color: rgb(34, 187, 234); font-size: 11px; font-family: verdana;"><em>- MCF HDR, Resp. L1 MPCI - DEPARTEMENT CHIMIE</em></span></div><div style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Tahoma, Verdana, Arial, Helvetica, sans-serif; font-size: 15px; line-height: 22px;"><span style="font-size: 11px; font-family: verdana;">Aix-Marseille Université - </span><span style="font-size: 11px; font-family: verdana;">ST JEROME - Avenue Escadrille Normandie Niemen - 13013 Marseille</span></div><div style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Tahoma, Verdana, Arial, Helvetica, sans-serif; font-size: 15px; line-height: 22px;"><span style="font-size: 11px; font-family: verdana;">Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50</span></div><div style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Tahoma, Verdana, Arial, Helvetica, sans-serif; font-size: 15px; line-height: 22px;"><span style="font-size: 12px; font-family: verdana;">Site : <a href="http://allos.up.univ-mrs.fr/pascal" title="http://allos.up.univ-mrs.fr/pascal" style="line-height: 20px; color: rgb(34, 187, 234); text-decoration: none;">http://allos.up.univ-mrs.fr/pascal</a> - Email : <a href="mailto:pascal.boulet@univ-amu.fr" style="line-height: 20px; color: rgb(34, 187, 234); text-decoration: none;">pascal.boulet@univ-amu.fr</a></span></div><div style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-family: Tahoma, Verdana, Arial, Helvetica, sans-serif; font-size: 15px; line-height: 22px;"><span style="line-height: 25px; color: rgb(0, 113, 185); font-size: 11px; font-family: verdana;"><em>Afin de respecter l'environnement, merci de n'imprimer cet email que si nécessaire.</em></span></div>
</div>
<br></div></body></html>