similar but not the same. The fitting parameter for V0 is 1165.10028469 A^3, Bulk modulus is 808.33GPa and its derivative is -31.54200148. The derivative is very different.
On Wed, Jul 29, 2015 at 11:03 AM, Paolo Giannozzi <[email protected]> wrote: > Which parameters do you obtain for V0 (equilibrium volume), K0 (bulk > modulus), dK0/dP? > > Paolo > > On Wed, Jul 29, 2015 at 4:13 PM, anyy zsj <[email protected]> wrote: > >> Thank you. But there is still a discrepancy for the following data set: >> 10.3 -54.420098694852939 >> 10.4 -54.716135146323531 >> 10.5 -54.894109787500000 >> 10.7 -53.873787839705884 >> modified ev.x gives 10.46368, while the fitting is 10.52255. >> >> >> On Wed, Jul 29, 2015 at 4:23 AM, Paolo Giannozzi <[email protected]> >> wrote: >> >>> Funny: one of the parameters of the fit is good for small unit cells, >>> but too small for larger cells. In line 162 of PW/tools/ev.f90, replace >>> deltapar(1) = 0.1d0 >>> with something larger: >>> deltapar(1) = 1.0d0 >>> should be sufficient. Thank you for noticing this >>> >>> Paolo >>> >>> On Tue, Jul 28, 2015 at 6:06 PM, anyy zsj <[email protected]> wrote: >>> >>>> This data set is actual calculated because I use a large supercell: >>>> 10.1 -48.570860572794118 >>>> 10.3 -49.368013045588235 >>>> 10.5 -49.714550792647060 >>>> 10.7 -49.667482497058820 >>>> 10.9 -49.305953287500003 >>>> But the fitting results are not compatible. >>>> >>>> 2015-07-28 12:01 GMT-04:00 Paolo Giannozzi <[email protected]>: >>>> >>>>> Please show me a set of data *produced by actual calculations* that >>>>> ev.x doesn't fit properly >>>>> >>>>> paolo >>>>> >>>>> On Tue, Jul 28, 2015 at 5:51 PM, anyy zsj <[email protected]> wrote: >>>>> >>>>>> Thank you very much! >>>>>> Sure it is angstrom. My concern is that with the same data, ev.x and >>>>>> the manual fitting give different results as shown above. So I believe >>>>>> something is there. >>>>>> The discrepancy is gone if I use a small lattice parameter. For >>>>>> example, if I scale the data by 1/3, both of them give the same results. >>>>>> So >>>>>> what's going on? >>>>>> >>>>>> 2015-07-28 11:44 GMT-04:00 Paolo Giannozzi <[email protected]>: >>>>>> >>>>>>> On Tue, Jul 28, 2015 at 5:26 PM, anyy zsj <[email protected]> wrote: >>>>>>> >>>>>>> >>>>>>>> 1.4989396432 -6.0466776328 >>>>>>>> 1.5430233198 -6.0795705718 >>>>>>>> 1.5879629631 -6.0993455319 >>>>>>>> 1.6804430727 -5.9859764266 >>>>>>>> The first column is volume and the second energy with Ry. After >>>>>>>> ev.x I input Ang, noncubic, 4, it gives me a results of 0.40 for >>>>>>>> minimal >>>>>>>> volume. It is certainly wrong. >>>>>>>> >>>>>>> >>>>>>> of course it is: ev.x assumes that the input data corresponds to a >>>>>>> physical EOS. Your data isn't physical: the volume is way too small >>>>>>> >>>>>>>> >>>>>>>> Another example for the below data: >>>>>>>> 10.1 -48.570860572794118 >>>>>>>> 10.3 -49.368013045588235 >>>>>>>> 10.5 -49.714550792647060 >>>>>>>> 10.7 -49.667482497058820 >>>>>>>> 10.9 -49.305953287500003 >>>>>>>> The first column is lattice constant with angstrom and the second >>>>>>>> energy with Ry. >>>>>>>> >>>>>>> After ev.x I input Ang, sc, 4, it gives me 10.50369, while I get a >>>>>>>> different value 10.57517 by fitting to the formula in PRB 28,5480 >>>>>>>> (1983) >>>>>>>> of Murnaghan's equation.: >>>>>>>> http://gilgamesh.cheme.cmu.edu/doc/software/jacapo/appendices/appendix-eos.html >>>>>>>> >>>>>>> >>>>>>> >>>>>>> sure that the first column is in angstrom and not a.u.? This is what >>>>>>> I get assuming it is in a.u.: >>>>>>> >>>>>>> # equation of state: murnaghan. chisq = 0.5402D-05 >>>>>>> # a0 = 10.5740 a.u., k0 =13776 kbar, dk0 = 4.17 d2k0 = 0.000 emin >>>>>>> = -49.73649 >>>>>>> # a0 = 5.59554 Ang, k0 =1377.7 GPa, V0 = ******* (a.u.)^3, V0 >>>>>>> =175.197 A^3 >>>>>>> >>>>>>> note the small value of the |chi|^2 (chisq) of the fit >>>>>>> >>>>>>> Paolo >>>>>>> >>>>>>> I have tested many groups of data but the discrepancy is there for >>>>>>>> those large lattice parameters. Does ev.x use another equation or >>>>>>>> something >>>>>>>> else I have missing? Thank you very much. >>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> Pw_forum mailing list >>>>>>>> [email protected] >>>>>>>> http://pwscf.org/mailman/listinfo/pw_forum >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Paolo Giannozzi, Dept. Chemistry&Physics&Environment, >>>>>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >>>>>>> Phone +39-0432-558216, fax +39-0432-558222 >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Pw_forum mailing list >>>>>>> [email protected] >>>>>>> http://pwscf.org/mailman/listinfo/pw_forum >>>>>>> >>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Pw_forum mailing list >>>>>> [email protected] >>>>>> http://pwscf.org/mailman/listinfo/pw_forum >>>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Paolo Giannozzi, Dept. Chemistry&Physics&Environment, >>>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >>>>> Phone +39-0432-558216, fax +39-0432-558222 >>>>> >>>>> _______________________________________________ >>>>> Pw_forum mailing list >>>>> [email protected] >>>>> http://pwscf.org/mailman/listinfo/pw_forum >>>>> >>>> >>>> >>>> _______________________________________________ >>>> Pw_forum mailing list >>>> [email protected] >>>> http://pwscf.org/mailman/listinfo/pw_forum >>>> >>> >>> >>> >>> -- >>> Paolo Giannozzi, Dept. Chemistry&Physics&Environment, >>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >>> Phone +39-0432-558216, fax +39-0432-558222 >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> [email protected] >>> http://pwscf.org/mailman/listinfo/pw_forum >>> >> >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > > -- > Paolo Giannozzi, Dept. Chemistry&Physics&Environment, > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > Phone +39-0432-558216, fax +39-0432-558222 > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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