[Pw_forum] How to read lattice constant from the output file of vc-relax
姚新欣
yaoxinxin at mail.sdu.edu.cn
Tue Mar 21 03:16:04 CET 2006
Dear all,
I execute a vc-relax calculation, the output file is like this:
===============================================================================
! total energy = -1513.15280271 ryd
estimated scf accuracy < 0.00000005 ryd
total magnetization = 9.00 Bohr mag/cell
absolute magnetization = 9.12 Bohr mag/cell
convergence has been achieved
Forces acting on atoms (Ry/au):
atom 1 type 1 force = -0.00090234 -0.00090236 -0.00060040
atom 2 type 3 force = 0.00025524 0.00025523 0.00032448
atom 3 type 4 force = -0.00023451 -0.00017762 0.00005756
atom 4 type 4 force = -0.00017761 -0.00023452 0.00005754
atom 5 type 4 force = -0.00014720 -0.00014719 -0.00004334
atom 6 type 5 force = 0.00021078 0.00021077 0.00024824
atom 7 type 2 force = 0.00072939 0.00072938 -0.00007323
atom 8 type 3 force = 0.00030165 0.00030164 0.00012308
atom 9 type 4 force = 0.00015559 0.00030045 -0.00009079
atom 10 type 4 force = 0.00030045 0.00015558 -0.00009079
atom 11 type 4 force = 0.00009477 0.00009474 0.00003522
atom 12 type 4 force = 0.00037284 0.00037287 0.00023032
atom 13 type 3 force = -0.00010083 -0.00010056 -0.00011395
atom 14 type 3 force = -0.00014817 -0.00014817 -0.00041716
atom 15 type 4 force = -0.00008397 0.00000251 0.00014874
atom 16 type 4 force = 0.00000267 -0.00008405 0.00014871
atom 17 type 4 force = -0.00011380 -0.00011380 -0.00003731
atom 18 type 4 force = -0.00051496 -0.00051490 0.00009309
Total force = 0.002310 Total SCF correction = 0.000828
entering subroutine stress ...
total stress (ryd/bohr**3) (kbar) P= -0.02
-0.00000170 -0.00000001 0.00000121 -0.25 0.00 0.18
-0.00000001 -0.00000170 0.00000121 0.00 -0.25 0.18
0.00000121 0.00000121 0.00000295 0.18 0.18 0.43
Parrinello-Rahman Damped Dynamics: convergence achieved, Efinal=
-1513.15280271
------------------------------------------------------------------------
Final estimate of lattice vectors (input alat units)
0.999218793 0.004883129 0.003921399
0.004883129 0.999218813 0.003921395
0.007955423 0.007955414 2.046656291
final unit-cell volume = 1413.6989 (a.u.)^3
input alat = 8.8445 (a.u.)
CELL_PARAMETERS (alat)
0.999218793 0.004883129 0.003921399
0.004883129 0.999218813 0.003921395
0.007955423 0.007955414 2.046656291
ATOMIC_POSITIONS (alat)
Fe1 -0.013056076 -0.013055086 0.002515773
Sn 0.497703713 0.497704623 0.354603733
O 0.719819040 0.305839769 0.021489138
O 0.305838560 0.719819831 0.021489205
O 0.842148687 0.842149758 0.340853449
H 0.219947019 0.219947779 0.341994037
Fe2 -0.013973823 -0.013972857 0.708191013
Sn 0.502042637 0.502043667 1.027340878
O 0.721364873 0.314430703 0.685223918
O 0.314429607 0.721365697 0.685223880
O 0.193695096 0.193695837 1.021346052
O 0.811306594 0.811307850 1.038377647
Sn 0.006642077 0.006643077 1.377214153
Sn 0.505715303 0.505716371 1.729800072
O 0.691583090 0.308332725 1.381201005
O 0.308331230 0.691583732 1.381201013
O 0.192814143 0.192814844 1.745050428
O 0.814855563 0.814856839 1.731663985
Writing output data file sno2.save
===============================================================================
I propose to execute another calculation of different replaced positions with
optimized atomic_positions as the initial condition,which I expect to spend less
time to finish,but I am puzzled by the optimized cell_parameters.From previous
outcomes,how can I determine the new cell_parameters and new atomic_positions in
the inputfile?
I have attempted to use a11(the first diagonal element of
cell_parameters)*celldm(1) as the new celldm(1),a33(the third diagonal element of
cell_parameters) as the new celldm(3),the output atomic_positions(alat) as the new
atomic_positions,and neglect all of the nondiagonal elements.
After the first self-consistent,I gain stresses with very large nondiagonal
elements than diagonal elements like that:
===============================================================================
total stress (ryd/bohr**3) (kbar) P= 3.20
0.00000417 0.00011011 0.00005447 0.61 16.20 8.01
0.00011011 0.00000418 0.00005447 16.20 0.61 8.01
0.00005447 0.00005447 0.00005700 8.01 8.01 8.39
===============================================================================
How can I adapt the input parameters to avoid this condition and get smaller
nondiagonal elements?
In the system block of the input file,there is a parameter "nosym".How does it
affect the final results? In my system(1*1*3 units supercells of SnO2
rutile-structure which include 18 atoms,and two Sn atoms are replaced by Fe and
one O atom by H),which value should I select,"true" or "false"?
Any help would be appreciated.
Best regards!
=======================================
X.X.Yao
School of Physics and Microelectronics,
Shandong University,
Jinan,Shandong 250100,
People's Republic of China.
=======================================
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