H

Name HamiltonianApplyPacked
Section Execution::Optimization
Type logical
Default yes

If set to yes (the default), Octopus will ‘pack’ the wave-functions when operating with them. This might involve some additional copying but makes operations more efficient. See also the related StatesPack variable.

Name HamiltonianVariation
Section Linear Response::Sternheimer
Type integer
Default hartree+fxc

The terms to be considered in the variation of the Hamiltonian. The external potential (V_ext) is always considered. The default is to include also the exchange-correlation and Hartree terms, which fully takes into account local fields. Just hartree gives you the random-phase approximation (RPA). If you want to choose the exchange-correlation kernel, use the variable XCKernel. For kdotp and magnetic em_resp modes, or if TheoryLevel = independent_particles, the value V_ext_only is used and this variable is ignored.

Options:

• V_ext_only:
  Neither Hartree nor XC potentials included.
  
• hartree:
  The variation of the Hartree potential only.
  
• fxc:
  The exchange-correlation kernel (the variation of the exchange-correlation potential) only.
  

Name HFSingularity
Section Hamiltonian::XC
Type integer
Default general

(Experimental) This variable selects the method used for the treatment of the singularity of the Coulomb potential in Hatree-Fock and hybrid-functional DFT calculations. This shoulbe be only applied for periodic systems and is only used for FFT kernels of the Poisson solvers.

Options:

• none:
  The singularity is replaced by zero.
  
• general:
  The general treatment of the singularity, as described in Carrier et al, PRB 75 205126 (2007). This is the default option
  
• fcc:
  The treatment of the singulariy as described in Gygi and Baldereschi, PRB 34, 4405 (1986). This is formaly valid for cubic systems only.
  
• spherical_bz:
  The divergence in q=0 is treated analytically assuming a spherical Brillouin zone
  

Name HFSingularityNk
Section Hamiltonian::XC
Type integer
Default 60

Number of k-point used (total number of k-points) is (2*Nk+1)^3) in the numerical integration of the auxiliary function f(q). See PRB 75, 205126 (2007) for more details. Only for HFSingularity=general.

Name HFSingularityNsteps
Section Hamiltonian::XC
Type integer
Default 7

Number of grid refinement steps in the numerical integration of the auxiliary function f(q). See PRB 75, 205126 (2007) for more details. Only for HFSingularity=general.