Energy difference too large for two phases

Posted on : October 14, 2021 (Thu) 20:29:29

by Hong Jian Zhao

Dear all,
I am calculating the energies for P4mm and Pm-3m phases of BaTiO3 using AkaiKKR. I expect to have E1 for P4mm and E2 for Pm-3m, with E1 being slightly lower than E2 (e.g., 0.05 eV/f.u.).
Now I got E1=-18411.087423216Ry for P4mm and E2=-18411.213851905Ry for Pm-3m. The energy of P4mm is far larger than Pm-3m by more than 1 eV/f.u.
Does anyone know what is wrong with my input? Thanks.

___P4mm inout____
c----------------------LaFeO3----------------------------------
go data/bto
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
trc 7.527 1.0112 1.0 90 90 90
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 2.2 srals mjw mag init
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 150 0.025
c------------------------------------------------------------
c ntyp
3
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 1 56 100
Ti 1 0 0.0 2 22 100
O 1 0 0.0 1 8 100
c------------------------------------------------------------
c natm
5
c------------------------------------------------------------
c atmicx atmtyp
0.0000000000000000a 0.0000000000000000b -0.0018753412898227c Ba
0.5000000000000000a 0.5000000000000000b 0.5096263877252621c Ti
0.5000000000000000a 0.5000000000000000b 0.9799191074932800c O
0.5000000000000000a 0.0000000000000000b 0.4859149300356401c O
0.0000000000000000a 0.5000000000000000b 0.4859149300356401c O
c------------------------------------------------------------

_____pm-3m inout______
c----------------------LaFeO3----------------------------------
go data/bto_pe
c------------------------------------------------------------
c brvtyp a c/a b/a alpha beta gamma
trc 7.527 1.0112 1.0 90 90 90
c------------------------------------------------------------
c edelt ewidth reltyp sdftyp magtyp record
0.001 2.2 srals mjw mag init
c------------------------------------------------------------
c outtyp bzqlty maxitr pmix
update 4 150 0.025
c------------------------------------------------------------
c ntyp
3
c------------------------------------------------------------
c type ncmp rmt field mxl anclr conc
Ba 1 0 0.0 1 56 100
Ti 1 0 0.0 2 22 100
O 1 0 0.0 1 8 100
c------------------------------------------------------------
c natm
5
c------------------------------------------------------------
c atmicx atmtyp
0.0000000000000000a 0.0000000000000000b -0.0000000000000000c Ba
0.5000000000000000a 0.5000000000000000b 0.5000000000000000c Ti
0.5000000000000000a 0.5000000000000000b 0.0000000000000000c O
0.5000000000000000a 0.0000000000000000b 0.5000000000000000c O
0.0000000000000000a 0.5000000000000000b 0.5000000000000000c O
c------------------------------------------------------------


P4mm output
itr= 56 neu= -0.0000 moment= 0.0000 te= -18411.08742334 err= -5.215
itr= 57 neu= -0.0000 moment= 0.0000 te= -18411.08742326 err= -5.314
itr= 58 neu= -0.0000 moment= 0.0000 te= -18411.08742336 err= -5.238
itr= 59 neu= -0.0000 moment= 0.0000 te= -18411.08742324 err= -4.765
itr= 60 neu= -0.0000 moment= 0.0000 te= -18411.08742326 err= -5.080
itr= 61 neu= -0.0000 moment= -0.0000 te= -18411.08742323 err= -5.579
itr= 62 neu= -0.0000 moment= -0.0000 te= -18411.08742332 err= -5.644
itr= 63 neu= -0.0000 moment= -0.0000 te= -18411.08742330 err= -5.687
itr= 64 neu= -0.0000 moment= -0.0000 te= -18411.08742329 err= -5.478
itr= 65 neu= -0.0000 moment= -0.0000 te= -18411.08742331 err= -5.436
itr= 66 neu= -0.0000 moment= -0.0000 te= -18411.08742325 err= -5.225
itr= 67 neu= -0.0000 moment= 0.0000 te= -18411.08742322 err= -5.860
itr= 68 neu= -0.0000 moment= -0.0000 te= -18411.08742322 err= -6.185
interval= 68 cpu time= 21.85 sec
sdftyp=mjw reltyp=srals dmpc= 0.10000
Ba Ti O_3
itr= 68 neu -0.0000 chr,spn 32.0000 -0.0000 intc,ints 5.3742 0.0000
rms err= -6.187 -7.738 -6.706 -6.185 -7.714 -6.711

ef= 0.6382463 0.6382463 def= 0.1602866 0.1602866
total energy= -18411.087423216


Pm-3m output
itr= 59 neu= -0.0000 moment= -0.0000 te= -18411.21385191 err= -4.899
itr= 60 neu= -0.0000 moment= -0.0000 te= -18411.21385192 err= -5.011
itr= 61 neu= -0.0000 moment= -0.0000 te= -18411.21385188 err= -5.023
itr= 62 neu= -0.0000 moment= -0.0000 te= -18411.21385192 err= -4.955
itr= 63 neu= -0.0000 moment= 0.0000 te= -18411.21385192 err= -5.385
itr= 64 neu= -0.0000 moment= 0.0000 te= -18411.21385180 err= -5.988
itr= 65 neu= -0.0000 moment= 0.0000 te= -18411.21385186 err= -5.985
itr= 66 neu= -0.0000 moment= 0.0000 te= -18411.21385185 err= -5.875
itr= 67 neu= -0.0000 moment= 0.0000 te= -18411.21385186 err= -5.859
itr= 68 neu= -0.0000 moment= 0.0000 te= -18411.21385185 err= -5.707
itr= 69 neu= -0.0000 moment= -0.0000 te= -18411.21385191 err= -6.167
interval= 69 cpu time= 15.67 sec
sdftyp=mjw reltyp=srals dmpc= 0.10000
Ba Ti O_3
itr= 69 neu -0.0000 chr,spn 32.0000 -0.0000 intc,ints 4.7013 0.0000
rms err= -6.173 -7.333 -6.249 -6.167 -7.364 -6.258

ef= 0.6027616 0.6027616 def= 0.1751673 0.1751673
total energy= -18411.213851905


Thanks a lot for your help.