cluster and MC understanding

[mozilla88]

Dear Alex and ATAT users,

I a ATAT CE new user, and am trying to use a binary system (Al-Ti) to learn how ATAT processes the CE and canonical MC. So far, I have several questions should be clarified.

1. In the clusters.out file, what do the first two blocks mean?
   1
   0.000000
   0

1
0.000000
1
1.000000 1.000000 1.000000
Are they the on-site clusters of the two elements (Al and Ti)?

2. For a configuration (e.g. one generated by maps), how to use the clusters.out file to output its number of each cluster figure, or how to show the cluster expansion of a configuration based on the clusters.out file?

3. To carry on the canonical MC, obtaining the average energy at a certain temperature, I have used the following command:
   emc2 -er=10 -cm -k=8.617e-5 -T0=500 -gs=2 -n 100 -eq 1000 -o=mc.out
   Is it correct for a canonical MC simulation?
   Are these "-eq" and "-n" numbers real MC steps? In the other words, how to determine the MC steps using the input "-eq" and "-n"?

4. In the canonical MC output file, mc.out, what does each column mean?
   500.000000 0 -0.036852 0.000000 -0.046235 0.000004 0 0 0 0 0 0.496711 1.000000 0.000000 -0.148630 0.337615 -0.140622 0.170963 0.057648

5. There are several other output files, htedate.dat, ltedat.out and mfdat.out. How to understand these file?

6. Is it possible to output the energy and snapshot of a certain steps (let’s say every 1000 steps)?
   Many thanks

[avdw]

1. In the clusters.out file, what do the first two blocks mean?
   1
   0.000000
   0

1
0.000000
1
1.000000 1.000000 1.000000
Are they the on-site clusters of the two elements (Al and Ti)?

They are the empty and point clusters.

2. For a configuration (e.g. one generated by maps), how to use the clusters.out file to output its number of each cluster figure, or how to show the cluster expansion of a configuration based on the clusters.out file?

The first number in each "block" of clusters.out is the multiplicity per unit cell. Just multiply this by (supercell’s number atom )/ (primitive cell number of atom)

3. To carry on the canonical MC, obtaining the average energy at a certain temperature, I have used the following command:
   emc2 -er=10 -cm -k=8.617e-5 -T0=500 -gs=2 -n 100 -eq 1000 -o=mc.out
   Is it correct for a canonical MC simulation?
   Are these "-eq" and "-n" numbers real MC steps? In the other words, how to determine the MC steps using the input "-eq" and "-n"?

yes but your -n value is way too small. -n should be >1000 or more
-n and -eq give the number of passes (=all sites have been attempted to flip one on average)

4. In the canonical MC output file, mc.out, what does each column mean?
   500.000000 0 -0.036852 0.000000 -0.046235 0.000004 0 0 0 0 0 0.496711 1.000000 0.000000 -0.148630 0.337615 -0.140622 0.170963 0.057648

see emc2 -h at the end. Some values are zero because they cannot be computed with cannonical MC.

5. There are several other output files, htedate.dat, ltedat.out and mfdat.out. How to understand these file?

Ignore these. They contain data to constuct low temperature, high temperature or mean field approximations.

6. Is it possible to output the energy and snapshot of a certain steps (let’s say every 1000 steps)?
   Many thanks

Use the -opss=[string] option.
This will output a snapshot everytime conditions changes. You can set a very small change in temperature (1 K) to see a run evolve essentially at constant temperature.