Dear CASTEP Support Team,

I am currently using CASTEP (version [insert version, e.g., 2020]) for DFT calculations and need to incorporate dispersion corrections for van der Waals interactions. Specifically, I would like to implement the Grimme’s DFT-D3 and DFT-D3(BJ) (Becke-Johnson damping) schemes in my simulations.

Could you kindly provide guidance on the following:

1. Required Input Parameters:

   • How are the C6 coefficients, damping function, and cutoff radii defined in CASTEP for DFT-D3 and D3-BJ?

   • Are specific keywords (e.g., DFT_D, D3_VERSION) needed in the .param or .cell files?

2. Implementation Steps:

   • Is there an automated way to enable these corrections via the GUI (e.g., Materials Studio), or must they be manually added to input files?

   • Are any additional libraries or scripts required?

3. Functional Compatibility:

   • Which exchange-correlation functionals (e.g., PBE, B3LYP) are validated with D3 and D3-BJ in CASTEP?

   • Is the scaling parameter s6 predefined for each functional, or must it be manually adjusted?

4. Validation Examples:

   • Are there tutorial cases or documentation (e.g., for molecular crystals or adsorption systems) demonstrating D3/BJ usage?

Thank you for your assistance. Please let me know if further details are required.

Best regards,
MuYunLiu