[Pw_forum] ambiguous results with vc-relax
It's up to what kind of system you are studying. For a system with orthorhombic, monoclinic or triclinic structure, my experience told me that vc-relax is much faster than the "static" method because in those cases you need to do a series of calculations for each parameter, b/a, c/a as well as volume for example of orthorhombic system. huiqun zhou @earth sciences, nanjing university, china - Original Message - From: jia chen To: pw_forum at pwscf.org Sent: Wednesday, August 25, 2010 2:51 AM Subject: [Pw_forum] ambiguous results with vc-relax sorry for interrupting you guys, I didn't follow the whole post before. Pressure calculations need very high ecutoff. And,according to my experience, vc-relax is supposed to be slow. So, I usually avoid vc-relax if possible... Last but not least, I am a student, maybe very wrong. Have a good day. -- Jia Chen Dept of Chemistry Princeton University Princeton, NJ 08544 -- ___ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100825/813f99e3/attachment.htm
[Pw_forum] ambiguous results with vc-relax
sorry for interrupting you guys, I didn't follow the whole post before. Pressure calculations need very high ecutoff. And,according to my experience, vc-relax is supposed to be slow. So, I usually avoid vc-relax if possible... Last but not least, I am a student, maybe very wrong. Have a good day. -- Jia Chen Dept of Chemistry Princeton University Princeton, NJ 08544 -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100824/28af1bbb/attachment-0001.htm
[Pw_forum] ambiguous results with vc-relax
Hi, Can you please elaborate on how you selected your ecutwfc? regards, On Mon, Aug 23, 2010 at 10:48 AM, jia chen wrote: > I did similar thing before, total energy doesn't need to converge... > > On Mon, Aug 23, 2010 at 2:22 AM, Guda Karthik > wrote: > > Hi, > > > > The total energy doesn't converge till 80 Ryd of ecutwfc. I am using > Ni > > and Ti USPPs (Ti.pbe-sp-van_ak.UPF, Ni.pbe-nd-rrkjus.UPF). My > calculations > > become very slow while using such a large kinetic energy cutoff. am I > doing > > something wrong here? > > > > regards, > > Karthik > > > > On Tue, Aug 17, 2010 at 4:46 PM, Stefano de Gironcoli > > > wrote: > >> > >> please note that the two outputs that you submitted ARE NOT examples of > >> vc-relaxation but of structural relaxation of the internal coordinates > >> only. Your question is anyway legittimate... > >> Are you sure to have converged the total energy of your system with > >> respect to cutoff to a sufficient level ? > >> when comparing different volumes one is using different basis sets in > >> the two cases. If convergence w.r.t. cutoff is not sufficient this can > >> lead to sudden decreases of the energy when increasing the volume. > >> > >> stefano > >> SISSA and DEMOCRITOS > >> > >> Guda Karthik wrote: > >> > Hi, > >> > > >> > Here are the input and output files. > >> > > >> > b19_Acklatpos_new.* - original structure > >> > > >> > b19_pwscf.* - scf calculation with a structure obtained after > >> > vc-relax > >> > > >> > Please have a look if they are of help. > >> > > >> > regards, > >> > Karthik > >> > > >> > On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi > >> > wrote: > >> > > >> > > >> >> On Aug 4, 2010, at 4:41 , Guda Karthik wrote: > >> >> > >> >> > >> >>> I am trying to relax an orthorhombic structure using vc-relax > >> >>> (celldofree - xyz). I start with a structure which is at a Pressure > >> >>> of -20.5 Kbar and at the end of the vc-relax I get a structure > >> >>> which is at a pressure of -0.21 Kbar. Surprisingly, the structure > >> >>> at pressure closer to zero is higher in energy than the original > >> >>> structure by 8 * 10^-4 eV/formula unit. All the symmetry elements > >> >>> have been conserved during relaxation and the initial and final > >> >>> structures are the same. I am not able to make sense of this > >> >>> result. I observe this inconsistency in my B2 structure as well. > >> >>> Please help regarding this. > >> >>> > >> >> hard to help without input and output > >> >> > >> >> P. > >> >> --- > >> >> Paolo Giannozzi, Dept of Physics, University of Udine > >> >> via delle Scienze 208, 33100 Udine, Italy > >> >> Phone +39-0432-558216, fax +39-0432-558222 > >> >> > >> >> > >> >> > >> >> ___ > >> >> Pw_forum mailing list > >> >> Pw_forum at pwscf.org > >> >> http://www.democritos.it/mailman/listinfo/pw_forum > >> >> > >> >> > >> > > >> > > >> > > >> > > >> > > > >> > > >> > ___ > >> > Pw_forum mailing list > >> > Pw_forum at pwscf.org > >> > http://www.democritos.it/mailman/listinfo/pw_forum > >> > >> ___ > >> Pw_forum mailing list > >> Pw_forum at pwscf.org > >> http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > > > -- > > Karthik Guda > > Graduate Student > > Materials Engineering > > Purdue University > > > > > > ___ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > > > -- > Jia Chen > > Dept of Chemistry > Princeton University > Princeton, NJ 08544 > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Karthik Guda Graduate Student Materials Engineering Purdue University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100824/7afbeb4a/attachment.htm
[Pw_forum] ambiguous results with vc-relax
I did similar thing before, total energy doesn't need to converge... On Mon, Aug 23, 2010 at 2:22 AM, Guda Karthik wrote: > Hi, > > ??? The total energy doesn't converge till 80 Ryd of ecutwfc. I am using Ni > and Ti USPPs (Ti.pbe-sp-van_ak.UPF, Ni.pbe-nd-rrkjus.UPF). My calculations > become very slow while using such a large kinetic energy cutoff. am I doing > something wrong here? > > regards, > Karthik > > On Tue, Aug 17, 2010 at 4:46 PM, Stefano de Gironcoli > wrote: >> >> please note that the two outputs that you submitted ARE NOT examples of >> vc-relaxation but of structural relaxation of the internal coordinates >> only. Your question is anyway legittimate... >> Are you sure to have converged the total energy of your system with >> respect to cutoff to a sufficient level ? >> when comparing ?different volumes one is using different basis sets in >> the two cases. If convergence w.r.t. cutoff is not sufficient this ?can >> lead to sudden decreases of the energy when increasing the volume. >> >> stefano >> SISSA and DEMOCRITOS >> >> Guda Karthik wrote: >> > Hi, >> > >> > ? ? Here are the input and output files. >> > >> > ? ? b19_Acklatpos_new.* - original structure >> > >> > ? ? b19_pwscf.* - scf calculation with a structure obtained after >> > vc-relax >> > >> > ? ? Please have a look if they are of help. >> > >> > regards, >> > Karthik >> > >> > On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi >> > wrote: >> > >> > >> >> On Aug 4, 2010, at 4:41 , Guda Karthik wrote: >> >> >> >> >> >>> I am trying to relax an orthorhombic structure using vc-relax >> >>> (celldofree - xyz). I start with a structure which is at a Pressure >> >>> of -20.5 Kbar and at the end of the vc-relax I get a structure >> >>> which is at a pressure of -0.21 Kbar. Surprisingly, the structure >> >>> at pressure closer to zero is higher in energy than the original >> >>> structure by 8 * 10^-4 eV/formula unit. All the symmetry elements >> >>> have been conserved during relaxation and the initial and final >> >>> structures are the same. I am not able to make sense of this >> >>> result. I observe this inconsistency in my B2 structure as well. >> >>> Please help regarding this. >> >>> >> >> hard to help without input and output >> >> >> >> P. >> >> --- >> >> Paolo Giannozzi, Dept of Physics, University of Udine >> >> via delle Scienze 208, 33100 Udine, Italy >> >> Phone +39-0432-558216, fax +39-0432-558222 >> >> >> >> >> >> >> >> ___ >> >> Pw_forum mailing list >> >> Pw_forum at pwscf.org >> >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> >> >> >> > >> > >> > >> > >> > >> > >> > ___ >> > Pw_forum mailing list >> > Pw_forum at pwscf.org >> > http://www.democritos.it/mailman/listinfo/pw_forum >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum > > > > -- > Karthik Guda > Graduate Student > Materials Engineering > Purdue University > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Jia Chen Dept of Chemistry Princeton University Princeton, NJ 08544
[Pw_forum] ambiguous results with vc-relax
Hi, The total energy doesn't converge till 80 Ryd of ecutwfc. I am using Ni and Ti USPPs (Ti.pbe-sp-van_ak.UPF, Ni.pbe-nd-rrkjus.UPF). My calculations become very slow while using such a large kinetic energy cutoff. am I doing something wrong here? regards, Karthik On Tue, Aug 17, 2010 at 4:46 PM, Stefano de Gironcoli wrote: > please note that the two outputs that you submitted ARE NOT examples of > vc-relaxation but of structural relaxation of the internal coordinates > only. Your question is anyway legittimate... > Are you sure to have converged the total energy of your system with > respect to cutoff to a sufficient level ? > when comparing different volumes one is using different basis sets in > the two cases. If convergence w.r.t. cutoff is not sufficient this can > lead to sudden decreases of the energy when increasing the volume. > > stefano > SISSA and DEMOCRITOS > > Guda Karthik wrote: > > Hi, > > > > Here are the input and output files. > > > > b19_Acklatpos_new.* - original structure > > > > b19_pwscf.* - scf calculation with a structure obtained after > vc-relax > > > > Please have a look if they are of help. > > > > regards, > > Karthik > > > > On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi >wrote: > > > > > >> On Aug 4, 2010, at 4:41 , Guda Karthik wrote: > >> > >> > >>> I am trying to relax an orthorhombic structure using vc-relax > >>> (celldofree - xyz). I start with a structure which is at a Pressure > >>> of -20.5 Kbar and at the end of the vc-relax I get a structure > >>> which is at a pressure of -0.21 Kbar. Surprisingly, the structure > >>> at pressure closer to zero is higher in energy than the original > >>> structure by 8 * 10^-4 eV/formula unit. All the symmetry elements > >>> have been conserved during relaxation and the initial and final > >>> structures are the same. I am not able to make sense of this > >>> result. I observe this inconsistency in my B2 structure as well. > >>> Please help regarding this. > >>> > >> hard to help without input and output > >> > >> P. > >> --- > >> Paolo Giannozzi, Dept of Physics, University of Udine > >> via delle Scienze 208, 33100 Udine, Italy > >> Phone +39-0432-558216, fax +39-0432-558222 > >> > >> > >> > >> ___ > >> Pw_forum mailing list > >> Pw_forum at pwscf.org > >> http://www.democritos.it/mailman/listinfo/pw_forum > >> > >> > > > > > > > > > > > > > > ___ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Karthik Guda Graduate Student Materials Engineering Purdue University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100823/e0ed091c/attachment.htm
[Pw_forum] ambiguous results with vc-relax
please note that the two outputs that you submitted ARE NOT examples of vc-relaxation but of structural relaxation of the internal coordinates only. Your question is anyway legittimate... Are you sure to have converged the total energy of your system with respect to cutoff to a sufficient level ? when comparing different volumes one is using different basis sets in the two cases. If convergence w.r.t. cutoff is not sufficient this can lead to sudden decreases of the energy when increasing the volume. stefano SISSA and DEMOCRITOS Guda Karthik wrote: > Hi, > > Here are the input and output files. > > b19_Acklatpos_new.* - original structure > > b19_pwscf.* - scf calculation with a structure obtained after vc-relax > > Please have a look if they are of help. > > regards, > Karthik > > On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi democritos.it>wrote: > > >> On Aug 4, 2010, at 4:41 , Guda Karthik wrote: >> >> >>> I am trying to relax an orthorhombic structure using vc-relax >>> (celldofree - xyz). I start with a structure which is at a Pressure >>> of -20.5 Kbar and at the end of the vc-relax I get a structure >>> which is at a pressure of -0.21 Kbar. Surprisingly, the structure >>> at pressure closer to zero is higher in energy than the original >>> structure by 8 * 10^-4 eV/formula unit. All the symmetry elements >>> have been conserved during relaxation and the initial and final >>> structures are the same. I am not able to make sense of this >>> result. I observe this inconsistency in my B2 structure as well. >>> Please help regarding this. >>> >> hard to help without input and output >> >> P. >> --- >> Paolo Giannozzi, Dept of Physics, University of Udine >> via delle Scienze 208, 33100 Udine, Italy >> Phone +39-0432-558216, fax +39-0432-558222 >> >> >> >> ___ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum
[Pw_forum] ambiguous results with vc-relax
Hi, Here are the input and output files. b19_Acklatpos_new.* - original structure b19_pwscf.* - scf calculation with a structure obtained after vc-relax Please have a look if they are of help. regards, Karthik On Sat, Aug 14, 2010 at 6:27 AM, Paolo Giannozzi wrote: > > On Aug 4, 2010, at 4:41 , Guda Karthik wrote: > > > I am trying to relax an orthorhombic structure using vc-relax > > (celldofree - xyz). I start with a structure which is at a Pressure > > of -20.5 Kbar and at the end of the vc-relax I get a structure > > which is at a pressure of -0.21 Kbar. Surprisingly, the structure > > at pressure closer to zero is higher in energy than the original > > structure by 8 * 10^-4 eV/formula unit. All the symmetry elements > > have been conserved during relaxation and the initial and final > > structures are the same. I am not able to make sense of this > > result. I observe this inconsistency in my B2 structure as well. > > Please help regarding this. > > hard to help without input and output > > P. > --- > Paolo Giannozzi, Dept of Physics, University of Udine > via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > > > ___ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Karthik Guda Graduate Student Materials Engineering Purdue University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100816/5c98314d/attachment-0001.htm -- next part -- A non-text attachment was scrubbed... Name: b19_Acklatpos_new.in Type: application/octet-stream Size: 1145 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20100816/5c98314d/attachment-0004.obj -- next part -- A non-text attachment was scrubbed... Name: b19_Acklatpos_new.out Type: application/octet-stream Size: 547033 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20100816/5c98314d/attachment-0005.obj -- next part -- A non-text attachment was scrubbed... Name: b19_pwscf.in Type: application/octet-stream Size: 1078 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20100816/5c98314d/attachment-0006.obj -- next part -- A non-text attachment was scrubbed... Name: b19_pwscf.out Type: application/octet-stream Size: 119850 bytes Desc: not available Url : http://www.democritos.it/pipermail/pw_forum/attachments/20100816/5c98314d/attachment-0007.obj
[Pw_forum] ambiguous results with vc-relax
On Aug 4, 2010, at 4:41 , Guda Karthik wrote: > I am trying to relax an orthorhombic structure using vc-relax > (celldofree - xyz). I start with a structure which is at a Pressure > of -20.5 Kbar and at the end of the vc-relax I get a structure > which is at a pressure of -0.21 Kbar. Surprisingly, the structure > at pressure closer to zero is higher in energy than the original > structure by 8 * 10^-4 eV/formula unit. All the symmetry elements > have been conserved during relaxation and the initial and final > structures are the same. I am not able to make sense of this > result. I observe this inconsistency in my B2 structure as well. > Please help regarding this. hard to help without input and output P. --- Paolo Giannozzi, Dept of Physics, University of Udine via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
[Pw_forum] ambiguous results with vc-relax
Hi, I am trying to relax an orthorhombic structure using vc-relax (celldofree - xyz). I start with a structure which is at a Pressure of -20.5 Kbar and at the end of the vc-relax I get a structure which is at a pressure of -0.21 Kbar. Surprisingly, the structure at pressure closer to zero is higher in energy than the original structure by 8 * 10^-4 eV/formula unit. All the symmetry elements have been conserved during relaxation and the initial and final structures are the same. I am not able to make sense of this result. I observe this inconsistency in my B2 structure as well. Please help regarding this. regards, -- Karthik Guda Graduate Student Materials Engineering Purdue University -- next part -- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100803/f8a26e76/attachment.htm
