Sounds like something wrong is going on. You may want to post your input files and some relevant snapshots of the output, although I am afraid that at that point others may be more knowledgeable than me … SB
> On 24 Aug 2018, at 13:57, Stella, Martina <[email protected]> wrote: > > Dear Prof. Baroni, > > thanks for prompt reply. > > So yes I am using NEB to find a barrier between two states. > > Before starting the NEB I have separately relaxed the geometries associated > with my two configurations (initial and final). Hence now I have two relaxed > geometries. > > I start the NEB using the relaxed geometries for these states as first and > last image and I use the option to freeze these configurations. > > When I start my NEB and I check for the absolute energies of these two images > (which supposedly are kept frozen so probably they just go through a SCF > cycle?), these energies are quite different from the ones I have from my > separate relaxations of the aforementioned geometries . So I was wondering if > this is what I should expect. > > But maybe I am missing something or thinking about it in the wrong way, I > will think about what you said. > > Thank again. > > Cheers. > > > > Martina Stella > Post-Doctoral researcher > Physics Department, King's College London > Strand,London WC2R 2LS UK > > From: users <[email protected] > <mailto:[email protected]>> on behalf of Stefano > Baroni <[email protected] <mailto:[email protected]>> > Sent: 24 August 2018 12:24:14 > To: Quantum Espresso users Forum > Subject: Re: [QE-users] Question on Initial and final energies in NEB > > Dear M., I do not quite get what the problem is. The solution may just be a > matter of definition. The “Minimum Energy Path” that the NEB is alleged to > find is the path in configuration space which *connects two minima* (hence > the answer to your question, I guess) and whose maximum energy (along the > path) is minimum (with respect to other paths). Put in a different way. What > are you using the NEB for? Finding an energy barrier, right? Between what? > Stable molecular configurations, right? (hence energy minima). Does this > help? SB > >> On 24 Aug 2018, at 13:12, Stella, Martina <[email protected] >> <mailto:[email protected]>> wrote: >> >> Hi, >> >> I am new to NEBs calculations and I am getting familiar with the method. I >> have a couple of questions, maybe trivial, but for which I don't have an >> answer yet. Hopefully someone can help. >> >> 1) How is the energy for the Initial and final structure estimated when I >> keep the two configurations frozen? >> 2)Should it be exactly the same as the final relaxed energies that I would >> get from completely separate calculations with the same simulation >> conditions and same geometries? >> 3) If they are not expected to be exactly the same which factors does the >> difference I may see depend on? >> >> Thanks. >> >> >> M. Stella >> Post-Doctoral researcher >> Physics Department, King's College London >> Strand,London WC2R 2LS UK >> >> _______________________________________________ >> users mailing list >> [email protected] <mailto:[email protected]> >> https://lists.quantum-espresso.org/mailman/listinfo/users >> <https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.quantum-espresso.org%2Fmailman%2Flistinfo%2Fusers&data=01%7C01%7Cmartina.stella%40kcl.ac.uk%7Cee3fd5575335452ca23708d609b42aa2%7C8370cf1416f34c16b83c724071654356%7C0&sdata=K2aWC4qlMkZBGvIorZJyp12XdpKWPi4f7oCg2WeCrME%3D&reserved=0> > — > Stefano Baroni - SISSA, Trieste - http://stefano.baroni.me > <https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstefano.baroni.me%2F&data=01%7C01%7Cmartina.stella%40kcl.ac.uk%7Cee3fd5575335452ca23708d609b42aa2%7C8370cf1416f34c16b83c724071654356%7C0&sdata=weKAciglLYYZeD0wQrpSbWxalk%2B6gijab9lWNuj%2Bq%2FI%3D&reserved=0>, > stefanobaroni (Skype) > > I believe in the despotism of human life and happiness against the liberty of > money and possessions - John Steinbeck > > > > > > > _______________________________________________ > users mailing list > [email protected] <mailto:[email protected]> > https://lists.quantum-espresso.org/mailman/listinfo/users > <https://lists.quantum-espresso.org/mailman/listinfo/users>
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