I've been running a test on the Al example file. Thought I might try a lattice constant optimisation, but no forces or stress is calculated.
Is this normal? Am I missing something blatantly obvious?
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
INPUT FILE
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ground state of aluminium. Try calculating the density of states by using
! tasks=10
tasks
2
! You can add notes to the INFO.OUT file using the "notes" block
notes
Simple calculation of the ground state of aluminium. Must check convergence
with respect to k-point set later.
Run by H. Golightly
avec
1.0 1.0 0.0
1.0 0.0 1.0
0.0 1.0 1.0
scale
3.00
! this is the relative path to the species files
sppath
'../../species/'
Are there plans to implement a cell optimisation in the future? On this note (pardon my ignorance) is there a way to calculate the stress/strain on a system with symmetric forces?
If not, would an inbuilt murnaghan equation of state calculation be useful? Is such a thing worth implementing?
Cheers,
Marty
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Hello!
I've been running a test on the Al example file. Thought I might try a lattice constant optimisation, but no forces or stress is calculated.
Is this normal? Am I missing something blatantly obvious?
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
INPUT FILE
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ground state of aluminium. Try calculating the density of states by using
! tasks=10
tasks
2
! You can add notes to the INFO.OUT file using the "notes" block
notes
Simple calculation of the ground state of aluminium. Must check convergence
with respect to k-point set later.
Run by H. Golightly
avec
1.0 1.0 0.0
1.0 0.0 1.0
0.0 1.0 1.0
scale
3.00
! this is the relative path to the species files
sppath
'../../species/'
atoms
1 : nspecies
'Al.in' : spfname
1 : natoms
0.0 0.0 0.0 0.0 0.0 0.0 : atposl, bfcmt
ngridk
4 4 4
vkloff
0.5 0.5 0.5
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end of OUTPUT
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+------------------------------+
| Self-consistent loop stopped |
+------------------------------+
Wrote STATE.OUT
Forces :
species : 1 (Al)
atom : 1
Hellmann-Feynman : 0.00000000 0.00000000 0.00000000
core correction : 0.00000000 0.00000000 0.00000000
IBS : 0.00000000 0.00000000 0.00000000
total force : 0.00000000 0.00000000 0.00000000
total magnitude : 0.00000000
Maximum force magnitude (target) : 0.000000000 ( 0.5000000000E-03)
Force convergence target achieved
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MAKEFILE
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MAKE = make
F90 = gfortran
F90_OPTS = -O3 -funroll-loops -ffast-math
F77 = gfortran
F77_OPTS = -O3 -funroll-loops -ffast-math
AR = ar
LIB_SYS =
LIB_LPK = lapack.a blas.a
LIB_FFT = fftlib.a
Hi,
The forces on an atom with inversion symmetry (like the aluminium example) will be zero.
To optimise the volume, you have to compute the total energy for several volumes and then fit a cubic or higher polynomial to the energy-volume graph.
Cheers,
Kay.
Excellent, thank you.
Are there plans to implement a cell optimisation in the future? On this note (pardon my ignorance) is there a way to calculate the stress/strain on a system with symmetric forces?
If not, would an inbuilt murnaghan equation of state calculation be useful? Is such a thing worth implementing?
Cheers,
Marty
To calculate the stress tensor, you must apply a general strain to the unit cell and compute the change in energy.
In the near future, EXCITING will do this automatically, either by finite differences or using an analytic formula.
If you would like to implement this, then drop me an email...
Cheers,
Kay.