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 HelmholtzCoulombGaugeTolerance
Section Calculation Modes::Test
Type float
Default 1e-5

If the vector potential should enforced to be in Coulomb Gauge, this variable defines the tolerance. The code will evaluate the following expression: $spacing * \frac{\nabla \cdot A}{|A|}$

Name HelmholtzEnforceCoulombGauge
Section Calculation Modes::Test
Type logical
Default yes

If true, the Vector Potential is enforced to be in Coulomb Gauge. See proof of eq 30 of: https://www.scirp.org/pdf/jmp_2016053115275279.pdf

Name HelmholtzVisualizeBoxes
Section Calculation Modes::Test
Type logical
Default no

If true, output the volume points for the three boxes of the Helmholtz surface correction.

1. The volume points of the system box
2. The inner mask for the system box. This region has the thickness of the stencil and it is used to set to zero the longitudinal or transverse field after computing the final divergence or curl (to avoid spikes)
3. The surface points of the system box

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 formally 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 in 3D, 1200 in 1D

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. Also used in 1D.

Name HFSingularityNsteps
Section Hamiltonian::XC
Type integer
Default 7 in 3D, 15 in 1D

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. Also used in 1D.

Name HybridCAMParameters
Section Hamiltonian::XC
Type block

This variable specifies the $\alpha, \beta, \omega$ for CAM-type hybrid functionals. Defaults are zero.