Dear ALPS users,

                         I am just a beginner in the ALPS simulations.The description of my question is as follows:

                                 As a practice exercise, I want to run the quantum montecarlo simulations using the spin ½ model defined in the ALPS library to calculate the Curie temperature (Tc) of bulk Iron metal by considering the BCC structure with a = 286.65 pm. Therefore, I have generated a BCC structure with first and second nearest neighbors. I have attached the structure related xml file “Fe.xml” along with this mail for your consideration.

                                Firstly, It is well known that the BCC structure has 8 first nearest neighbors placed at ( ±½, ±½, ±½ ) positions with respect to the vertex at (0, 0, 0). In the xml file I have defined only two nearest neighbor edges connecting the (0, 0, 0) to (½, ½, ½ ) and (-½, ½, ½ )positions in the unit cell. Thereafter, when i viewed the structure by using lattice-preview program in the periodic boundary condition with L=2,it is showing all 8 nearest neighbors. My question is that due to the definition of periodicity does the simulation takes into account all 8 nearest neighbors even though if I don't define the 6 other nearest neighbors explicitly in the unit cell.

                                    Secondly, along with the above mentioned issue on the definition of the structure, I am kindly requesting you to provide me some insights regarding how to calculate the Curie temperature of Iron metal by using the ALPS simulation in terms of which programs I have to use in order to accomplish this task. A simple example describing this task would be of very great help.

                                       If you are finding my questions being trivial ones, I apologize to you for that. But, these confusions and problems are stopping me to proceed further, I read through the web documentation of ALPS, but could not solve them. Hence, I am kindly looking forward for your suggestions and help. I thank you in advance for your time and consideration.

With best regards

Sunil

Max Planck Institute, Dresden