[Pw_forum] Re: cut-off radius for radial integrations
Virginie Quequet
virginie.quequet at polytechnique.fr
Tue Feb 22 14:46:09 CET 2005
Tank you for your reply.
It seems quite systematic, because my first example was for titanium and
I tried for silicon with the input of example01 (david) with a pseudo-potential
with non-local part defined up to 60 a.u. and I obtain this
rcut = 10 a.u.
! total energy = -15.89013028 ryd
estimated scf accuracy < 6.7E-09 ryd
band energy sum = 0.62621995 ryd
one-electron contribution = 4.74024554 ryd
hartree contribution = 1.07806794 ryd
xc contribution = -4.80868510 ryd
ewald contribution = -16.89975867 ryd
convergence has been achieved
Forces acting on atoms (Ry/au):
atom 1 type 1 force = 0.00000000 0.00000000 0.00000000
atom 2 type 1 force = 0.00000000 0.00000000 0.00000000
Total force = 0.000000 Total SCF correction = 0.000000
entering subroutine stress ...
total stress (ryd/bohr**3) (kbar) P= -17.45
-0.00011860 0.00000000 0.00000000 -17.45 0.00 0.00
0.00000000 -0.00011860 0.00000000 0.00 -17.45 0.00
0.00000000 0.00000000 -0.00011860 0.00 0.00 -17.45
rcut = 60 a.u.
! total energy = -15.90406433 ryd
estimated scf accuracy < 5.9E-09 ryd
band energy sum = 0.61224706 ryd
one-electron contribution = 4.72633379 ryd
hartree contribution = 1.07803417 ryd
xc contribution = -4.80867362 ryd
ewald contribution = -16.89975867 ryd
convergence has been achieved
Forces acting on atoms (Ry/au):
atom 1 type 1 force = 0.00000000 0.00000000 0.00000000
atom 2 type 1 force = 0.00000000 0.00000000 0.00000000
Total force = 0.000000 Total SCF correction = 0.000000
entering subroutine stress ...
total stress (ryd/bohr**3) (kbar) P= -25.60
-0.00017399 0.00000000 0.00000000 -25.60 0.00 0.00
0.00000000 -0.00017399 0.00000000 0.00 -25.60 0.00
0.00000000 0.00000000 -0.00017399 0.00 0.00 -25.60
Virginie Quequet
On Thursday 17 February 2005 16:22, Virginie Quequet wrote:
> I try to change to 60 a.u. the cut-off radius for radial integration,
you shouldn't: the radial integration is performed on short-range
functions only. Beyond 10 a.u. all you have is numerical noise.
> which is put to 10 a.u. in the code (rcut variable). It seems to me
> that it should change very little the results, but it is not the case.
please provide a test case (input and output)
Paolo
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