Dear Suddhasattwa Ghosh, While I do not understand all of this, especially not what you mean by figures, and "small unit cell that reproduces the correlations" it seems that you will need to write your own MC code for that, but can do it based on ALPS and thus make use of the ALPS. Matthias On Nov 28, 2011, at 12:43 PM, Suddhasattwa Ghosh wrote:

Dear Sir, Thank you very much for the mail. The possible algorithm for generating random structures is 1. Begin with known correlations of ideal crystal 2. Determine good structures to represent ideal crystal 3. Convert lattice into Ising-like model 4. Replace atoms {A,B} with spins, Sigma={-1,+1} 5. Consider a set of “figures” .Define local correlation function as the product of spins 6. Calculate lattice average by summing over symmetrically equivalent figures over all sites

Goal: Generate small unit cell that reproduces the correlations found in random alloys using a MC code

Thank you Suddhasattwa Ghosh

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Today's Topics:

1. Re: Suggestions on ALPS Simulations (Matthias Troyer)

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Message: 1 Date: Sat, 26 Nov 2011 17:22:38 +0100 From: Matthias Troyer <troyer@phys.ethz.ch> To: comp-phys-alps-users@lists.phys.ethz.ch Subject: Re: [ALPS-users] Suggestions on ALPS Simulations Message-ID: <D69E3090-F741-4BBA-A182-89E32703FA79@phys.ethz.ch> Content-Type: text/plain; charset="iso-8859-1"

Hi,

You need to tell us which model you want to simulate. Certainly ALPS can help you write a MC code for your problem, but I don't think that a MC code for your specific problem exists.

Matthias

On 23 Nov 2011, at 12:09, Suddhasattwa Ghosh wrote:

...

Dear Sir,

We would like to address the following problems using the ALPS package.

May I kindly request if you could inform us if these problems could be done using this package?

Problem 1

I consider a bcc phase with 3.64 A as lattice parameter. We assume A, B or C (could be Ni,Ti and Nb) can either occupy (0,0,0) position.

I also assume X(A)=0.40 X(B)=0.40 X(C)=0.20 as composition variables

Now, I consider a 40 atom cell which can mimic the most random alloy with this composition.

Can I use your code to get the most random alloy for A, B and C. That is to say, getting the structure of this alloy with a 40 atom cell satisfying the

compositions using MC simulations at T=298.15 K

Can we add any number of elements if we are to construct a disordered alloy of say, 5 elements? Can it be done?

Problem 2

I consider a rhombohedral phase with 15-16 A approx. as lattice parameters. I have five different inequivalent positions which can either be occupied by A or B (say Ni and Fe)

I assume composition variables as X(A)=0.60 X(B)=0.40

Can in this case a 40 atom cell be used to generate the most random structure using MC simulations at T=298.15 K

Could you please suggest on these issues Sir and inform if ALPS could be used for these cases.

With regards

Suddhasattwa Ghosh