[SIESTA-L] Grimmer Dispersion Correction

2014-02-06 Por tôpico Kraemer, Tobias
Dear Brad,


Thanks for your valuable comments, this confirms what I was thinking. Thanks 
also for letting me know
About the need for re-compiling. I will look into this.

I take that when specifying the parameters list within this block, the C6 
parameter always refers to the first atom defining the pair (and therefore
remains constant for a specific sub-block), while the van-der-Waals radii 
naturally refer to the sum of both. Hence,

%block MM.potentials
1 1   C6(1) R0(1)+R0(1)
1 2   C6(1) R0(1)+R0(2)
1 3   C6(1) R0(1)+R0(2)
2 2   C6(2) R0(2) +R0(2)
2 3   C6(2) R0(2) +R0(3)
%endblock MM.Potentials

Is this correct?

I am still a bit unsure about the 1.66, but have found d=20 in the paper 
indeed. Thank for pointing this out to me.

Best

Tobias




Dr. Tobias Kraemer
Research Associate
Institute of Chemical Sciences
School of Engineering  Physical Sciences
Heriot-Watt University
Edinburgh EH14 4AS
United Kingdom
* t.krae...@hw.ac.uk
* +44 (0)131 451 3259






From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On Behalf Of 
Brad Wells
Sent: 04 February 2014 14:31
To: siesta-l@uam.es
Subject: Re: [SIESTA-L] Grimmer Dispersion Correction

Hi Tobias,

(1)  Unfortunately for 7 different atoms you need explicitly specify the 28 
unique pairwise potentials.  This is tedious, which is why I have a program 
that does it for me.  One thing to note in the release versions of SIESTA there 
is only the memory space for 10 pair potentials.  If you want to correctly use 
Grimme's dispersion correction you will have to change maxMMpot in the 
molecularmechanics.F90 and re-compile the program.  If you don't do this SIESTA 
will only use the first 10 potentials that you specify.

(2)  Grimme uses J nm^(6) mol^(-1), SIESTA uses eV angstrom^(6), so the 
conversion factor is approx. 10.3641

(3)  I am not sure about the 1.66.  From Grimme's 2006 paper for PBE this 
should be 0.75.  The D value is the same as in Grimme's paper.

I hope this helps you.

Brad Wells.
Monash University.


On 5/02/2014 1:07 AM, Kraemer, Tobias wrote:
Dear all,


I would like to try out adding Grimme's dispersion correction to my 
calculation. From the manual and the list archive
I understand that this can be done, however, some points are unclear to me.

The parameters need to be defined in the MM.Potentials block, and if I am not 
mistaken, this needs to be done
for each pair wise interaction between atom types. For my system containing 7 
different atoms, this seems to be
quite tedious. Is there a more straight forward way of doing this? Certainly I 
could restrict the number to only include
nearest neighbours, but this is difficult to decide a priory. So, there would 
be a large number of pairs that would need to be considered here.

Nonetheless, if I should do it this way how would I translate between different 
units. It appears that  the original Grimme paper reports these parameters in 
Jnm^(6)mol^(-1) which differs from SIESTA standard units (I stumbled upon this 
discussion in the archive, however, I couldn't find
A conclusive answer. Unfortunately I also seem to be unable to recover the post 
from the archive, despite some time spent searching).

My last question addresses the 2 parameters MM.Grimme.D and MM.Grimme.S6. The 
latter is by default set to 1.66 for a DZP basis, however,
For which functional is this the default. Can this value be ised straight away 
with PBE? Where does this value come from?
Likewise, can the default value for .D be used straight away?

Thanks for your help

Tobias






Dr. Tobias Kraemer
Research Associate
Institute of Chemical Sciences
School of Engineering  Physical Sciences
Heriot-Watt University
Edinburgh EH14 4AS
United Kingdom
* t.krae...@hw.ac.ukmailto:t.krae...@hw.ac.uk
* +44 (0)131 451 3259





Sunday Times Scottish University of the Year 2011-2013
Top in the UK for student experience
Fourth university in the UK and top in Scotland (National Student Survey 2012)

We invite research leaders and ambitious early career researchers to join us in 
leading and driving research in key inter-disciplinary themes. Please see 
www.hw.ac.uk/researchleadershttp://www.hw.ac.uk/researchleaders for further 
information and how to apply.

Heriot-Watt University is a Scottish charity registered under charity number 
SC000278.



- 
Sunday Times Scottish University of the Year 2011-2013
Top in the UK for student experience
Fourth university in the UK and top in Scotland (National Student Survey 2012)

We invite research leaders and ambitious early career researchers to 
join us in leading and driving research in key inter-disciplinary themes. 
Please see www.hw.ac.uk/researchleaders for further information and how
to apply.

Heriot-Watt University is a Scottish charity
registered under charity number SC000278.



[SIESTA-L] Structure does not converge

2014-02-06 Por tôpico Kraemer, Tobias
Dear Herbert,


Thanks for your reply. I have added these lines now (some of which I had 
included already, but
Some were not in my input), and that indeed gives the right output. The ANI 
file can be read by
Chemcraft as you said. I also experience some difficulties with gdis showing 
the structures 
Properly, as you pointed out in your last post. There appears to be a large 
number of structure
plotted on top of each other. But still, in principle it is working now. 
Looking at the xyz file 
with Chemcraft is also very useful at this stage. 


Best

Tobias




Dr. Tobias Kraemer
Research Associate
Institute of Chemical Sciences
School of Engineering  Physical Sciences
Heriot-Watt University 
Edinburgh EH14 4AS
United Kingdom
uut.krae...@hw.ac.uk
tt+44 (0)131 451 3259





-Original Message-
From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On Behalf Of 
Herbert Fruchtl
Sent: 04 February 2014 15:29
To: siesta-l@uam.es
Subject: Re: [SIESTA-L] Structure does not converge

Hi Tobias,

You need to set the WriteCoorStep value. Here's a section from a random input I 
once ran:

WriteCoorInitaltrue
WriteCoorSteptrue
WriteForces true
WriteCoorXmol   true
WriteCoorCerius false
WriteMDXmol true
WriteMDhistory  true

The first two lines tell it to write the geometry (initial and in every step) 
into the output file. WriteCoorXmol tells it to write the final geometry into 
seed.xyz. WriteMDXmol creates seed.ANI, which has the format of an xyz 
movie (I usually create a link ln -s test.ANI trj.xyz. As I mentioned before, 
the xyz format doesn't contain cell information, but is more reliable when used 
with gdis. Anything with MD in it also applies to geometry optimisation (which 
you can just see as a special case of dynamics).

HTH,

   Herbert

On 04/02/14 13:38, Kraemer, Tobias wrote:
 Dear Herbert,


 I have installed gdis in the meantime. I was able to open the fdf file 
 without problems, And I can nicely visualise the unit cell that I used 
 as input. However, gdis doesn't find Any coordinates in the SIESTA 
 output (you refer to this as the .sot file). I am not sure I am 
 looking at the right file. My output doesn't contain coordinates which 
 are updated During the run, only the input geometry in the @reading standard 
 input section, later on Only forces are reported.

 Best


 Tobias




 -Original Message-
 From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On 
 Behalf Of Herbert Fruchtl
 Sent: 28 January 2014 11:53
 To: siesta-l@uam.es
 Subject: Re: [SIESTA-L] Structure does not converge

 Hi Tobias,

 Try gdis for visualisation. It can shoe you a movie from a .sot 
 (standard SIESTA output), even though it sometimes does it wrong. 
 Haven't found out yet when this happens. You can also create an xyz 
 (not periodic, but readable by most viewing
 programs) movie with the WriteMDxmol flag. Rename the .ANI file to something 
 ending with .xyz.

 Which optimizer do you use? I find CG safest.

 HTH,

 Herbert

 On 28/01/14 10:07, Kraemer, Tobias wrote:
 Dear Abraham,

 Thanks for your detailed response. I did check the convergence of my 
 calculations, and I should have included this in

 My previous post. So here is what happens in this calculation:

 1)The force oscillates quite significantly within the set 500 
 optimisation steps, and taken that the MaxForceTol is set to 0.04 
 eV/Ang,

 This seems to be far from convergence to me. Here is a snapshot of 
 the last 10 steps.

 Max0.580458constrained

  Max0.174727constrained

  Max0.082654constrained

  Max0.080264constrained

  Max0.115938constrained

  Max0.354063constrained

  Max0.164293constrained

  Max0.236174constrained

  Max0.114993constrained

  Max0.060479constrained

 2)The unit cell seems to undergo some significant change, at least to my eye.

 outcell: Cell vector modules (Ang)   :9.534700   11.749500   15.878700

 outcell: Cell vector modules (Ang)   :9.675640   11.898404   16.056706

 outcell: Cell vector modules (Ang)   :9.901185   12.136756   16.341658

 [...]

 outcell: Cell vector modules (Ang)   :9.017619   11.059155   15.490068

 outcell: Cell vector modules (Ang)   :9.018024   11.060081   15.486998

 outcell: Cell vector modules (Ang)   :9.018673   11.061565   15.482088

 outcell: Cell vector modules (Ang)   :9.018155   11.060380   15.486008

 outcell: Cell vector modules (Ang)   :9.018614   11.058782   15.482515

 outcell: Cell vector modules (Ang)   :9.018461   11.059315   15.483680

 outcell: Cell vector modules (Ang)   :9.020634   11.060348   15.484791

 outcell: Cell vector modules (Ang)   :9.024112   11.062001   15.486571

 Inspecting the last structure, I can at least say that the structure 
 does

RE: [SIESTA-L] Structure does not converge

2014-02-04 Por tôpico Kraemer, Tobias
Dear Herbert,


I have installed gdis in the meantime. I was able to open the fdf file without 
problems, 
And I can nicely visualise the unit cell that I used as input. However, gdis 
doesn't find
Any coordinates in the SIESTA output (you refer to this as the .sot file). I am 
not sure
I am looking at the right file. My output doesn't contain coordinates which are 
updated
During the run, only the input geometry in the @reading standard input 
section, later on
Only forces are reported. 

Best


Tobias


  

-Original Message-
From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On Behalf Of 
Herbert Fruchtl
Sent: 28 January 2014 11:53
To: siesta-l@uam.es
Subject: Re: [SIESTA-L] Structure does not converge

Hi Tobias,

Try gdis for visualisation. It can shoe you a movie from a .sot (standard 
SIESTA output), even though it sometimes does it wrong. Haven't found out yet 
when this happens. You can also create an xyz (not periodic, but readable by 
most viewing
programs) movie with the WriteMDxmol flag. Rename the .ANI file to something 
ending with .xyz.

Which optimizer do you use? I find CG safest.

HTH,

   Herbert

On 28/01/14 10:07, Kraemer, Tobias wrote:
 Dear Abraham,

 Thanks for your detailed response. I did check the convergence of my 
 calculations, and I should have included this in

 My previous post. So here is what happens in this calculation:

 1)The force oscillates quite significantly within the set 500 
 optimisation steps, and taken that the MaxForceTol is set to 0.04 
 eV/Ang,

 This seems to be far from convergence to me. Here is a snapshot of the 
 last 10 steps.

 Max0.580458constrained

 Max0.174727constrained

 Max0.082654constrained

 Max0.080264constrained

 Max0.115938constrained

 Max0.354063constrained

 Max0.164293constrained

 Max0.236174constrained

 Max0.114993constrained

 Max0.060479constrained

 2)The unit cell seems to undergo some significant change, at least to my eye.

 outcell: Cell vector modules (Ang)   :9.534700   11.749500   15.878700

 outcell: Cell vector modules (Ang)   :9.675640   11.898404   16.056706

 outcell: Cell vector modules (Ang)   :9.901185   12.136756   16.341658

 [...]

 outcell: Cell vector modules (Ang)   :9.017619   11.059155   15.490068

 outcell: Cell vector modules (Ang)   :9.018024   11.060081   15.486998

 outcell: Cell vector modules (Ang)   :9.018673   11.061565   15.482088

 outcell: Cell vector modules (Ang)   :9.018155   11.060380   15.486008

 outcell: Cell vector modules (Ang)   :9.018614   11.058782   15.482515

 outcell: Cell vector modules (Ang)   :9.018461   11.059315   15.483680

 outcell: Cell vector modules (Ang)   :9.020634   11.060348   15.484791

 outcell: Cell vector modules (Ang)   :9.024112   11.062001   15.486571

 Inspecting the last structure, I can at least say that the structure 
 does not blow-up or do anything that is unpredicted (I am looking at

 This from the perspective of someone who has done gas phase DFT / ab 
 initio calculations on molecular/cluster systems, but I guess

 There is some common ground here). I need to figure out a way though 
 how to visualise single steps of the optimisation itself,

 Like I would do in one of my more regular calculations. I am sure 
 there must be a way to do this with XCrysden (the program I am using

 Currently).

 So following what you have said in your email, I will try your 
 suggestions and play around with the optimisation protocol.

 However, what still worries me is if this possibly has something to do 
 with the
 (downloaded) pseudopotentials I have chosen.

 I feel there are a lot of things that can go wrong here

 Anyways, I will keep you posted. Thanks again for your comments.

 Tobias

 *From:*siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] *On 
 Behalf Of *Abrah

 am Hmiel
 *Sent:* 24 January 2014 20:40
 *To:* Siesta, Self-Consistent DFT LCAO program, 
 http://www.uam.es/siesta
 *Subject:* Re: [SIESTA-L] Structure does not converge

 Tobias,

 I'm curious, what do the results of the following commands look like?

 1) fgrep constrained 1.out

 2) fgrep outcell: Cell vector modules (Ang) 1.out

 *where 1.out is the name of the output log file

 You don't have to print them and send them our way, as they'll be very 
 large, but what can you say about them in general? Are the forces 
 fluctuating about a small amount that isn't quite as small as the 
 threshold you've chosen? Are the lattice parameters very different 
 from what you started with? Is everything blowing up?

 In general, this is what I do. Instead of doing one relaxation with a 
 very large number of CG steps, perform several in steps, making sure 
 the UseSaveData flag is set to true so that you don't have to come up 
 with a new density matrix each time and can use the previous CG trajectory

[SIESTA-L] Grimmer Dispersion Correction

2014-02-04 Por tôpico Kraemer, Tobias
Dear all,


I would like to try out adding Grimme's dispersion correction to my 
calculation. From the manual and the list archive
I understand that this can be done, however, some points are unclear to me.

The parameters need to be defined in the MM.Potentials block, and if I am not 
mistaken, this needs to be done
for each pair wise interaction between atom types. For my system containing 7 
different atoms, this seems to be
quite tedious. Is there a more straight forward way of doing this? Certainly I 
could restrict the number to only include
nearest neighbours, but this is difficult to decide a priory. So, there would 
be a large number of pairs that would need to be considered here.

Nonetheless, if I should do it this way how would I translate between different 
units. It appears that  the original Grimme paper reports these parameters in 
Jnm^(6)mol^(-1) which differs from SIESTA standard units (I stumbled upon this 
discussion in the archive, however, I couldn't find
A conclusive answer. Unfortunately I also seem to be unable to recover the post 
from the archive, despite some time spent searching).

My last question addresses the 2 parameters MM.Grimme.D and MM.Grimme.S6. The 
latter is by default set to 1.66 for a DZP basis, however,
For which functional is this the default. Can this value be ised straight away 
with PBE? Where does this value come from?
Likewise, can the default value for .D be used straight away?

Thanks for your help

Tobias






Dr. Tobias Kraemer
Research Associate
Institute of Chemical Sciences
School of Engineering  Physical Sciences
Heriot-Watt University
Edinburgh EH14 4AS
United Kingdom
* t.krae...@hw.ac.uk
* +44 (0)131 451 3259




- 
Sunday Times Scottish University of the Year 2011-2013
Top in the UK for student experience
Fourth university in the UK and top in Scotland (National Student Survey 2012)

We invite research leaders and ambitious early career researchers to 
join us in leading and driving research in key inter-disciplinary themes. 
Please see www.hw.ac.uk/researchleaders for further information and how
to apply.

Heriot-Watt University is a Scottish charity
registered under charity number SC000278.



RE: [SIESTA-L] Structure does not converge

2014-01-28 Por tôpico Kraemer, Tobias
Dear Abraham,


Thanks for your detailed response. I did check the convergence of my 
calculations, and I should have included this in
My previous post. So here is what happens in this calculation:


1)  The force oscillates quite significantly within the set 500 
optimisation steps, and taken that the MaxForceTol is set to 0.04 eV/Ang,
This seems to be far from convergence to me. Here is a snapshot of the last 10 
steps.

Max0.580458constrained
   Max0.174727constrained
   Max0.082654constrained
   Max0.080264constrained
   Max0.115938constrained
   Max0.354063constrained
   Max0.164293constrained
   Max0.236174constrained
   Max0.114993constrained
   Max0.060479constrained


2)  The unit cell seems to undergo some significant change, at least to my 
eye.

outcell: Cell vector modules (Ang)   :9.534700   11.749500   15.878700
outcell: Cell vector modules (Ang)   :9.675640   11.898404   16.056706
outcell: Cell vector modules (Ang)   :9.901185   12.136756   16.341658
[...]
outcell: Cell vector modules (Ang)   :9.017619   11.059155   15.490068
outcell: Cell vector modules (Ang)   :9.018024   11.060081   15.486998
outcell: Cell vector modules (Ang)   :9.018673   11.061565   15.482088
outcell: Cell vector modules (Ang)   :9.018155   11.060380   15.486008
outcell: Cell vector modules (Ang)   :9.018614   11.058782   15.482515
outcell: Cell vector modules (Ang)   :9.018461   11.059315   15.483680
outcell: Cell vector modules (Ang)   :9.020634   11.060348   15.484791
outcell: Cell vector modules (Ang)   :9.024112   11.062001   15.486571

Inspecting the last structure, I can at least say that the structure does not 
blow-up or do anything that is unpredicted (I am looking at
This from the perspective of someone who has done gas phase DFT / ab initio 
calculations on molecular/cluster systems, but I guess
There is some common ground here). I need to figure out a way though how to 
visualise single steps of the optimisation itself,
Like I would do in one of my more regular calculations. I am sure there must be 
a way to do this with XCrysden (the program I am using
Currently).

So following what you have said in your email, I will try your suggestions and 
play around with the optimisation protocol.
However, what still worries me is if this possibly has something to do with the 
(downloaded) pseudopotentials I have chosen.
I feel there are a lot of things that can go wrong here

Anyways, I will keep you posted. Thanks again for your comments.


Tobias


From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On Behalf Of 
Abrah


am Hmiel
Sent: 24 January 2014 20:40
To: Siesta, Self-Consistent DFT LCAO program, http://www.uam.es/siesta
Subject: Re: [SIESTA-L] Structure does not converge

Tobias,

I'm curious, what do the results of the following commands look like?
1) fgrep constrained 1.out
2) fgrep outcell: Cell vector modules (Ang) 1.out
*where 1.out is the name of the output log file

You don't have to print them and send them our way, as they'll be very large, 
but what can you say about them in general? Are the forces fluctuating about a 
small amount that isn't quite as small as the threshold you've chosen? Are the 
lattice parameters very different from what you started with? Is everything 
blowing up?

In general, this is what I do. Instead of doing one relaxation with a very 
large number of CG steps, perform several in steps, making sure the UseSaveData 
flag is set to true so that you don't have to come up with a new density matrix 
each time and can use the previous CG trajectory information as well:
1) Do one with MD.NumCGSteps ~ 10 and MD.MaxCGDispl ~ 0.15 Ang, to perform a 
very coarse relaxation (it is unlikely you will meet the threshold, and that's 
okay. You're not done). Call the output file 1.out or something like that.
2) Do one with MD.NumCGSteps ~ 20 and MD.MaxCGDispl ~ 0.05 Ang, to perform a 
coarse relaxation. Call the output file 2.out
3) Do one with MD.NumCGSteps ~ 20 and MD.MaxCGDispl ~ 0.01 Ang, to perform a 
finer relaxation. Call the output file 3.out
...
as many successive steps as you need with as much fineness as desired or until 
you meet your force convergence criteria, at which point you will have a 
relaxed structure. If 'everything is blowing up' then you may have to take 
another look at your simulation parameters. Sometimes choosing the wrong Pulay 
mixing parameters will prevent your simulation from falling into a convergence 
basin, so another look at that may be helpful. Transition metals sometimes call 
for using small (~0.01 or smaller) DM.MixingWeight with a kick every several 
steps (see the manual).

Warm regards,

--
Abraham Hmiel
Katherine Belz Groves Fellow in Nanoscience
Xue Group, SUNY College of Nanoscale Science and Engineering
http://abehmiel.net/about


On Fri, Jan 24, 2014 at 1:09 PM, Kraemer, Tobias 
t.krae

RE: [SIESTA-L] Structure does not converge

2014-01-28 Por tôpico Kraemer, Tobias
Hi Herbert,


Thanks for your suggestions. Will try gdis, sounds like what I am looking for.
For the optimizer I did use conjugate gradients indeed. 

Tobias






-Original Message-
From: siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] On Behalf Of 
Herbert Fruchtl
Sent: 28 January 2014 11:53
To: siesta-l@uam.es
Subject: Re: [SIESTA-L] Structure does not converge

Hi Tobias,

Try gdis for visualisation. It can shoe you a movie from a .sot (standard 
SIESTA output), even though it sometimes does it wrong. Haven't found out yet 
when this happens. You can also create an xyz (not periodic, but readable by 
most viewing
programs) movie with the WriteMDxmol flag. Rename the .ANI file to something 
ending with .xyz.

Which optimizer do you use? I find CG safest.

HTH,

   Herbert

On 28/01/14 10:07, Kraemer, Tobias wrote:
 Dear Abraham,

 Thanks for your detailed response. I did check the convergence of my 
 calculations, and I should have included this in

 My previous post. So here is what happens in this calculation:

 1)The force oscillates quite significantly within the set 500 
 optimisation steps, and taken that the MaxForceTol is set to 0.04 
 eV/Ang,

 This seems to be far from convergence to me. Here is a snapshot of the 
 last 10 steps.

 Max0.580458constrained

 Max0.174727constrained

 Max0.082654constrained

 Max0.080264constrained

 Max0.115938constrained

 Max0.354063constrained

 Max0.164293constrained

 Max0.236174constrained

 Max0.114993constrained

 Max0.060479constrained

 2)The unit cell seems to undergo some significant change, at least to my eye.

 outcell: Cell vector modules (Ang)   :9.534700   11.749500   15.878700

 outcell: Cell vector modules (Ang)   :9.675640   11.898404   16.056706

 outcell: Cell vector modules (Ang)   :9.901185   12.136756   16.341658

 [...]

 outcell: Cell vector modules (Ang)   :9.017619   11.059155   15.490068

 outcell: Cell vector modules (Ang)   :9.018024   11.060081   15.486998

 outcell: Cell vector modules (Ang)   :9.018673   11.061565   15.482088

 outcell: Cell vector modules (Ang)   :9.018155   11.060380   15.486008

 outcell: Cell vector modules (Ang)   :9.018614   11.058782   15.482515

 outcell: Cell vector modules (Ang)   :9.018461   11.059315   15.483680

 outcell: Cell vector modules (Ang)   :9.020634   11.060348   15.484791

 outcell: Cell vector modules (Ang)   :9.024112   11.062001   15.486571

 Inspecting the last structure, I can at least say that the structure 
 does not blow-up or do anything that is unpredicted (I am looking at

 This from the perspective of someone who has done gas phase DFT / ab 
 initio calculations on molecular/cluster systems, but I guess

 There is some common ground here). I need to figure out a way though 
 how to visualise single steps of the optimisation itself,

 Like I would do in one of my more regular calculations. I am sure 
 there must be a way to do this with XCrysden (the program I am using

 Currently).

 So following what you have said in your email, I will try your 
 suggestions and play around with the optimisation protocol.

 However, what still worries me is if this possibly has something to do 
 with the
 (downloaded) pseudopotentials I have chosen.

 I feel there are a lot of things that can go wrong here

 Anyways, I will keep you posted. Thanks again for your comments.

 Tobias

 *From:*siesta-l-requ...@uam.es [mailto:siesta-l-requ...@uam.es] *On 
 Behalf Of *Abrah

 am Hmiel
 *Sent:* 24 January 2014 20:40
 *To:* Siesta, Self-Consistent DFT LCAO program, 
 http://www.uam.es/siesta
 *Subject:* Re: [SIESTA-L] Structure does not converge

 Tobias,

 I'm curious, what do the results of the following commands look like?

 1) fgrep constrained 1.out

 2) fgrep outcell: Cell vector modules (Ang) 1.out

 *where 1.out is the name of the output log file

 You don't have to print them and send them our way, as they'll be very 
 large, but what can you say about them in general? Are the forces 
 fluctuating about a small amount that isn't quite as small as the 
 threshold you've chosen? Are the lattice parameters very different 
 from what you started with? Is everything blowing up?

 In general, this is what I do. Instead of doing one relaxation with a 
 very large number of CG steps, perform several in steps, making sure 
 the UseSaveData flag is set to true so that you don't have to come up 
 with a new density matrix each time and can use the previous CG trajectory 
 information as well:

 1) Do one with MD.NumCGSteps ~ 10 and MD.MaxCGDispl ~ 0.15 Ang, to 
 perform a very coarse relaxation (it is unlikely you will meet the 
 threshold, and that's okay. You're not done). Call the output file 1.out or 
 something like that.

 2) Do one with MD.NumCGSteps ~ 20 and MD.MaxCGDispl ~ 0.05 Ang, to 
 perform a coarse relaxation

[SIESTA-L] Structure does not converge

2014-01-24 Por tôpico Kraemer, Tobias
Dear SIESTA users,


I am very new to the SIESTA code, so to start with I am familiarising myself 
with the protocols involved to run
calculations with the code. I am trying to reproduce some numbers from a paper, 
where a crystal structure
(triclinic system) of a Ru-allyl complex was relaxed (Organometallics, 2013, 
32, 3784). I have set up a SIESTA input for relaxing
this structure, using PBE with the default DZP basis sets for all atoms, along 
with pseudopotentials from the SIESTA
database (I am aware that this might not be the best choice, but to start with 
it might be a fair option). The calculation
seems to fail to converge to a minimum structure and stops after the default 
500 opt cycles. This makes me suspicious,
since my feeling is that the structure should have converged within 500 cycles. 
The SCF cycles converge fine.

I have attached my input file below, the structure is read in from an external 
xyz file (attached). I have used as many
default settings for the moment as possible. I would appreciate if you could 
share your experience and advice on this subject.

Is such an input in principle a good starting point for the task at hand? What 
could I improve?
Would the use of a Monkhorst-Pack grid be a better choice? There are some other
Questions regarding dispersion corrections but first I need to play around with 
what I
understand from the manual.


Kind regards, thanks for everybody's help. Really trying to learn how to get 
reliable results.


Tobias



SystemName  [Ru(AcCN)2(Cp*)(eta3-phenylallyl) unit cell
SystemLabel ru_allyl
NumberOfAtoms   160
NumberOfSpecies 7
WriteMullikenPop1

%block ChemicalSpeciesLabel
1  44 Ru  # Species index, atomic number, species label
2  15 P
 3   9 F
4   8 O
 5   7 N
6   6 C
7   1 H
%endblock ChemicalSpeciesLabel

MeshCutoff   400.0 Ry

NetCharge 0.00

XC.functional GGA
XC.authors PBE
SpinPolarized.false.

DM.NumberPulay4
DM.MixingWeight   0.3
DM.UseSaveDM  .true.

NeglNonOverlapInt False

AtomicCoordinatesFormat  NotScaledCartesianAng
AtomicCoordinatesAndAtomicSpecies  ru_allylinput.xyz

LatticeConstant 1.0 Ang

%block LatticeParameters
   9.5347 11.7495 15.8787 109.395 96.719 100.965
%endblock LatticeParameters

WriteCoorXmol True
WriteForces .true.
WriteMullikenPop 1

SaveDeltaRho  .true.



MD.TypeOfRun   cg   # Type of dynamics: Conjugate gradients
MD.NumCGsteps   500 # number of CG steps
MD.MaxCGDispl  0.15 Ang
MD.MaxForceTol 0.04 eV/Ang
MD.UseSaveXV   yes
MD.VariableCell.true.






Dr. Tobias Kraemer
Research Associate
Institute of Chemical Sciences
School of Engineering  Physical Sciences
Heriot-Watt University
Edinburgh EH14 4AS
United Kingdom
* t.krae...@hw.ac.uk
* +44 (0)131 451 3259




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ru_allylinput.xyz
Description: ru_allylinput.xyz


ru_allyl.fdf
Description: ru_allyl.fdf