Dear All,
I am trying these days for the first time MD simulations with
SIESTA.
In particular, what I want to study is some molecular anchoring on top of
MO slabs.
Anyway, I am always getting very weird behaviour in my calculations.
I mean, I have optimized my structure properly. The optimization run went
fine and I take the .xyz file as input for my MD run.
I simply want to thermalize the system at 300K. Nevertheless, every time I
do it, the temperature after about 20 cycles "collapses" to 0 K and I am
extremely frustrated since I can not figure out the reason for it.
The xx.MDE is indeed
# Step T (K) E_KS (eV) E_tot (eV) Vol (A^3) P (kBar)
1 298.50 -72915.25721 -72908.41095 9301.380 -227.979
2 297.15 -72915.37035 -72908.41837 9301.380 -227.915
3 294.85 -72915.61083 -72908.44044 9301.380 -227.631
4 280.08 -72915.67760 -72908.45274 9301.380 -227.189
5 248.95 -72915.42802 -72908.44212 9301.380 -226.761
6 211.49 -72915.05018 -72908.42164 9301.380 -226.589
7 182.30 -72914.86424 -72908.41174 9301.380 -226.783
8 166.34 -72915.00001 -72908.42722 9301.380 -227.281
9 154.26 -72915.23280 -72908.44891 9301.380 -227.907
10 135.78 -72915.28496 -72908.44857 9301.380 -228.522
11 113.35 -72915.19180 -72908.43472 9301.380 -228.989
12 96.07 -72915.17286 -72908.42776 9301.380 -229.299
13 87.49 -72915.33295 -72908.43430 9301.380 -229.408
14 83.15 -72915.58301 -72908.44694 9301.380 -229.368
15 76.61 -72915.76703 -72908.45495 9301.380 -229.257
16 65.83 -72915.81699 -72908.45301 9301.380 -229.175
17 54.63 -72915.81079 -72908.44452 9301.380 -229.214
18 48.59 -72915.89534 -72908.44147 9301.380 -229.459
.....
And this is switching the Harris Energy on. For the KS case the reduction
is even faster....
Can you tell me what is wrong with my fdf. Please consider that pseudos
are "standard" from the library.
Thanks in advance for any possible suggestion.
With best regards,
Giacomo
here the fdf
SystemName MD
SystemLabel MD
NumberOfAtoms 250
NumberOfSpecies 4
%block ChemicalSpeciesLabel
1 22 Ti
2 8 O
3 6 C
4 1 H
%endblock ChemicalSpeciesLabel
PAO.BasisSize DZP
XC.functional LDA
XC.authors CA
ElectronicTemperature 1500.0 K
LatticeConstant 1. Ang
%block LatticeVectors
11.355 0 0
0 20.4786 0
0 0 40.
%endblock LatticeVectors
%block kgrid_Monkhorst_Pack
1 0 0 0.5 #1
0 1 0 0.5 #1
0 0 1 0.5 #1
%endblock Kgrid_Monkhorst_Pack
MeshCutoff 200.0 Ry #400.0 Ry
DM.MixingWeight 0.008 # 0.008
DM.NumberPulay 5
DM.Tolerance 1.d-4 #1.d-4
SolutionMethod diagon
ElectronicTemperature 500 K
MaxSCFIterations 500
#SCFMustConverge .true.
WriteDM .true.
WriteEigenvalues .false.
PAO.EnergyShift 0.01 Ry
MD.TypeOfRun Nose
HarrisFunctional T
WriteCoorStep .true.
WriteForces .true.
WriteMDHistory .true.
MD.UseSaveXV T
MD.Length.Time.Step 1.0 fs
MD.Final.Time.Step 10000
MD.InitialTemperature 300 K
MD.TargetTemperture 300 K
MD.NoseMass 100.0 Ry*fs**2
MD.MaxForceTol 0.05 eV/Ang # 0.05 eV/Ang
UseSaveData .true.
%block GeometryConstraints
position from 1 to 72
%endblock GeometryConstraints
AtomicCoordinatesFormat Ang
%block AtomicCoordinatesAndAtomicSpecies
...
%endblock AtomicCoordinatesAndAtomicSpecies
--
* * * * * * * * * * * * * * * * * * * * * * * * *
* Giacomo Giorgi *
* Ph.D. *
* Dipartimento di Chimica e Istituto di *
* Scienze e Tecnologie Molecolari ISTM-CNR *
* Universita' degli Studi di Perugia *
* Via Elce di Sotto 8 06123 Perugia Italia *
* Tel: +39 075-5855618 Fax: +39 075-5855606 *
* E-mail: giac_at_thch.unipg.it *
* * * * * * * * * * * * * * * * * * * * * * * * *
"Oltre le illusioni di Timbuctu'
e le gambe lunghe di Babalu' c'era questa strada...
Questa strada zitta che vola via come una farfalla,
una nostalgia, nostalgia al gusto di curacao...
Forse un giorno meglio mi spieghero'..."
(Paolo Conte, "Hemingway")
