use MPI in the function of Local_Orbital_Charge::cal_dk_k about abacus-develop

[hongriTianqi]

@Satinelamp Thanks for your tests! This function actually has MPI function, which are included in the Grid_Technique. We are working to optimize its performance. Please expect newer versions of ABACUS. If no further problems on this function, I will close this issue.

[hongriTianqi]

• Identify the specific code file or section with the code quality issue.
• Investigate the issue and determine the root cause.
• Research best practices and potential solutions for the identified issue.
• Refactor the code to improve code quality, following the suggested solution.
• Ensure the refactored code adheres to the project's coding standards.
• Test the refactored code to ensure it functions as expected.
• Update any relevant documentation, if necessary.
• Submit a pull request with the refactored code and a description of the changes made.

[WHUweiqingzhou]

@Satinelamp
In our latest version v3.4.0, class Local_Orbital_Charge has been replaced by a new class DensityMatrix in the main procedure more or less, and the MPI transfer function cal_dk_k is replaced by a new function transfer_DM2DtoGrid(). The problem has been solved in this refactor.
If you are interested in the new implement, you can also check the performance of transfer_DM2DtoGrid().

[hongriTianqi]

@Satinelamp Could you please test if this issue still exists? If it has been solved, we will close this issue. Thanks!