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<div class="moz-cite-prefix">Dear Varadharajan,<br>
<br>
I do not know if it make sense or not in general, anyway this
possibility is not available at the moment. All atoms of atomic
type i will be constrained to have local magnetization equal to
starting_magnetization(i). However, you can try to edit the
magnetic constraint subroutine in PW/src/add_bfield.f90 to suit
your needs.<br>
<br>
Regards<br>
<br>
<br>
GS<br>
Materials Theory, ETH Zurich<br>
<br>
<br>
On 03/05/2014 05:25 AM, Varadharajan Srinivasan wrote:<br>
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<div dir="ltr">Dear Gabriele,
<div><br>
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<div>To add to Paresh's question is it possible (and does it
make sense) to constrain the magnetisation of only a few atoms
and not the others? While the target here seems to be atoms 3
and 4 the other atoms are being made to pay the price so to
speak. </div>
<div><br>
</div>
<div>One option, in the present framework, is to constrain the
values of magnetisation of all other atoms to their respective
lambda=0 values. Could this speed up the convergence with
lambda? </div>
<div><br>
</div>
<div>Thanks,</div>
<div>Vardha.</div>
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<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Tue, Mar 4, 2014 at 7:18 PM,
Gabriele Sclauzero <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:gabriele.sclauzero@mat.ethz.ch"
target="_blank">gabriele.sclauzero@mat.ethz.ch</a>></span>
wrote:<br>
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What about the evolution of the constrained
magnetization?<br>
(Please also make sure that the values specified in
starting_magnetization make sense, as suggested by L.
Paulatto Sir).<br>
<br>
My suggestion was to vary lambda in small steps (say
0.5). I'm surprised that you managed to converge the
calculation with such high lambda values.<br>
<br>
Anyway, the constrain energy looks way too large, your
system is probably still far from the target.<br>
<br>
<br>
GS
<div>
<div class="h5"><br>
<br>
On 03/04/2014 01:57 PM, paresh rout wrote:<br>
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<div>Respected Sclauzero sir,<br>
</div>
Thanks for your reply. According to your
suggestion, I varied my Lambda value from
0,5,.......150 ry. Although calculated
constrained energy are decreasing but upto 150
ry the constrained energy and the estimated scf
accuracy are not the same order. Here I am
providing my constrained energy with various
lambda value.<br>
<br>
</div>
Lambda Constraint_Energy<br>
0 0.00000000<br>
5 36.93411685<br>
10 69.54815816 <br>
15 6.65653915 estimated scf accuracy
< 7.6E-13 Ry<br>
20 7.88546052<br>
25 8.88385707<br>
30 9.71513061 <br>
35 10.42697250<br>
40 11.05006563<br>
45 11.60072229<br>
50 12.08887057<br>
70 13.54966033<br>
80 14.05546257<br>
90 14.45159513<br>
100 14.75974550<br>
110 14.99680383<br>
120 15.17624003<br>
130 15.30876396 <br>
140 15.40310437 estimated scf
accuracy < 9.9E-13 Ry
<br>
150 15.46632278 estimated scf
accuracy < 9.9E-13 Ry<br>
<br>
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<div class="gmail_extra"><br>
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<div class="gmail_quote">On Tue, Mar 4, 2014 at
3:06 PM, Sclauzero Gabriele <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:gabriele.sclauzero@mat.ethz.ch"
target="_blank">gabriele.sclauzero@mat.ethz.ch</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0
0 0 .8ex;border-left:1px #ccc
solid;padding-left:1ex">Dear Paresh,<br>
<br>
in my understanding you should start with
a very small lambda value (e.g. 0.1), make
sure the calculation has converged (not always
trivial), then restart with a larger value.<br>
It is important to tune the steps by which you
increase lambda. Increasing it by steps of 5
seems too much to me, I would suggest you to
try much smaller steps, say between 0.1 and
0.5.<br>
<br>
There are two reasons why the energy
increases: the first is because you are
constraining your system out of its ground
state, but that's exactly what one would
expect. The other is the contribution from the
penalty energy (E_constrain, it should be
printed after each scf step), which is used to
impose the constraint.<br>
An important thing is that this energy term is
not physical and becomes negligible once your
system reaches the target state.Therefore one
should monitor this constraint energy,
together with the constrained quantity, and
make sure it goes to zero at some point.<br>
<br>
Once lambda is large enough and you reached
the targeted state, E_constrain should be
negligible w.r.t. the total energy and of the
same order of the estimated scf accuracy. From
that point on, the energy should not change if
you further increase lambda, because your
system fulfills (almost) exactly the
constraint, so that E_constrain should stay to
a very low value.<br>
<br>
HTH<br>
<br>
<br>
GS<br>
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