Malathe, I usually use vc-relax, so I dont know if it is the same in the relaxation calculation you are using, but the last step of vc-relax is a scf calculation with the relaxed structure. I just checked an old output file and you can check for this line in your relax output:
End of BFGS Geometry Optimization Final enthalpy = -395.6714252266 Ry [...] A final scf calculation at the relaxed structure. The G-vectors are recalculated for the final unit cell Results may differ from those at the preceding step. [...] ! total energy = -395.66904355 Ry The energies are slightly different. If you are not satisfied with this energy you could of course perform a scf calculation on the relaxed structure and check that the energy is the same. Good luck, Brad -------------------------------------------------------- Bradly Baer Graduate Research Assistant, Walker Lab Interdisciplinary Materials Science Vanderbilt University ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Malathe Khalil <malathe.ze...@gmail.com> Sent: Sunday, May 17, 2020 11:43 AM To: Quantum ESPRESSO users Forum <users@lists.quantum-espresso.org> Subject: Re: [QE-users] (no subject) Dear Fabrizio I want to calculate the adsorption energy of a molecule on a surface. So I need the total energy of the clean slab. Can I just take the total energy from relax calculations output or I have to run scf ? Thanks Malathe On Sun, 17 May 2020, 6:04 pm Fabrizio Cossu, <fabrizio.co...@apctp.org<mailto:fabrizio.co...@apctp.org>> wrote: On Sun, 17 May 2020 at 22:19, Malathe Khalil <malathe.ze...@gmail.com<mailto:malathe.ze...@gmail.com>> wrote: Dear QE users What is the difference between the total energy generated by relax calculations and scf calculations? A structural relaxation is a scf calculation. Perhaps you mean a fixed point scf calculation, i.e. without updating the positions. When I do relax calculations do I need to do scf calculations also? It depends on what you want to do. Do you want to compute some quantity self-consistently? AFAIK, some calculations require a different parameter set WRT the relaxation. Thanks Malathe _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.max-centre.eu%2Fquantum-espresso&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7C8c38d872a03b4530f4db08d7fa817eca%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C1%7C637253306403248372&sdata=1zBMO0gyZXTG0VC7EAUUOJQZkBe2cOYryB%2BpzA1n1i8%3D&reserved=0>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.quantum-espresso.org%2Fmailman%2Flistinfo%2Fusers&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7C8c38d872a03b4530f4db08d7fa817eca%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C1%7C637253306403258371&sdata=uw4H2%2BskQbIl4csuZTN%2BAG9JXXsqSz94luLjXEpgWuM%3D&reserved=0> _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.max-centre.eu%2Fquantum-espresso&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7C8c38d872a03b4530f4db08d7fa817eca%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C1%7C637253306403258371&sdata=mBBcvFRvpd7fsr19FWFi%2FYDrrGU9pwXjDnxs%2FwaRB%2FA%3D&reserved=0>) users mailing list users@lists.quantum-espresso.org<mailto:users@lists.quantum-espresso.org> https://lists.quantum-espresso.org/mailman/listinfo/users<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.quantum-espresso.org%2Fmailman%2Flistinfo%2Fusers&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7C8c38d872a03b4530f4db08d7fa817eca%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C1%7C637253306403268359&sdata=zrs65af7%2BynbX3vk5JD8dnASHFFvL8eQtyniXSwBReg%3D&reserved=0>
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