Efficient implementation of a van der Waals density functional: application to double-wall carbon nanotubes

Area of Science:

• Computational Physics
• Materials Science
• Quantum Chemistry

Background:

• Accurate simulation of large systems requires efficient computational methods.
• Van der Waals density functional theory (vdW-DF) is crucial for describing nonlocal correlation energy.
• Previous vdW-DF implementations were computationally expensive for large systems.

Purpose of the Study:

• To present an efficient implementation of the van der Waals density functional.
• To enable first-principles simulations of large-scale soft matter and biomolecular systems.
• To accelerate the computation of total energy and atomic forces.

Main Methods:

• Factorization of the integration kernel in vdW-DF.
• Utilization of fast Fourier transforms (FFTs) for computation.
• Achieving O(NlogN) computational complexity.

Main Results:

• A dramatic speedup in calculations compared to O(N^2) methods.
• The computational overhead is a small fraction of the total cost for large systems.
• Successful application to calculate binding energies and rotational/translational barriers in double-wall carbon nanotubes.

Conclusions:

• The developed method significantly enhances the efficiency of vdW-DF calculations.
• This opens up possibilities for first-principles simulations of large, complex systems.
• The method is validated by its application to carbon nanotube systems.