Recent content by xxh418

Hi all, I am trying to using OpenMP to parallelize a loop in C++. The iterator for the loop is defined by std::list using C++ standard library containers. The following is an example: for (std::list<int>::iterator it=mylist.begin() ; it != mylist.end(); ++it) std::cout << ' ' <<...

Hi Drgreg, Thank you very much for your answer. I setup the opinion buffer="no" in "write", then the problem is solved. Thanks again. Xu

Hi all, I encounted a write file problem for Fortran 90. I appreciate it a lot if you can help me. I open a file at the beginning of the program. Then everytime I rewind the unit number and write one new line to the first line of the file (the previous data on the first line is replaced)...

Hi Maple Thank you for your reply. What does the "dilute concentrations" mean? In random walk, there could be only one atom to diffuse in the solute. For the diffusion equation, there will be a concentration gradient. For the mass(atom) diffusion in solid crystals, for example, the Li...

Hi all: Now I have a question about the concept of diffusion coefficient in two cases: the diffusion equation (J=DdT/dx) and the random walk (tao^2=6Dt). My quesion is the two D in two equations are the same or different. If they are different, is there any relationship between them? Best Xu

Mapes: I still can not get it. I drew the crystal lattice and think it over and over. Just assume we have simple cubic structure. The diffusion tension is [D 0 0; 0 D 0; 0 0 D]. If we rotate an small angle thita. Then the new diffusion coefficient in the new direction would be D multiplied by a...

Mapes, Thanks for your reply. I am talking about the diffusivity. But I can not understand how the diffusivity can be all the same in all directions. For example, for Si crystal, If I pick {110},{1 1 -1}{1 1 2} directions, the arrangement of the atoms in every directions are very different...

Hi all: I have a question about the anisotropy properties of SINGLE CRYSTAL. The definition of the isotropy in WiKi is that the properties of the materials are the identical in ALL directions. If so, none of the single crystal is isotropic even though you can find such XYZ planes that the...