Hello QE users I want to find U value for CeO2 which is having 81 atoms. I already calculated this value by using linear response ( http://hjklol.mit.edu/content/calculating-hubbard-u). I got the U value initially in negative numbers in this case *diago_thr_init* value was default, so that I changed *diago_thr_init* to 10^-11 then I got U value as 0.00881. From literature I found this value should be around 4.5 - 7eV (Phy. Rev. B 75, 035109, 2007͒). I have some doubts regarding this calculation

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Is that correct, occupations means I took value in the name of *"N of occupied +U levels" *(i.e sum of Tr[ns(na)] values on all 27 Ce atoms)? What is the unit for value I got (0.00881)? (Ry or eV or any other ) Is U parameter value depend on number of atoms in unit cell? Is there any other mistake I done in my input file ? (input file attached) *Conditions I applied in my calculations:* Surface calculation with vacuum 15A First three layers relaxed (two oxygen and one ceria layers) remaining are frozen Thanks in advance and I will be greatly appreciated for your help (input file and results of my calculation attached) Phanikumar Research Scholar Indian Institute of Technology Kharagpur India

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CeO2.in**

*Description:* Binary data

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Results_u_cal.xlsx**

*Description:* MS-Excel 2007 spreadsheet

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