Section GW

• Parameters influencing the RI-G0W0 method

• Section path: CP2K_INPUT / ATOM / METHOD / XC / WF_CORRELATION / RI_RPA / GW

• This section cannot be repeated.

• Subsections

  • BSE
  • IC
  • PERIODIC
  • PRINT

• Keywords

  • SECTION_PARAMETERS
  • ANALYTIC_CONTINUATION
  • BSE
  • CORR_MOS_OCC
  • CORR_MOS_VIRT
  • CROSSING_SEARCH
  • EPS_ITER
  • EV_GW_ITER
  • FERMI_LEVEL_OFFSET
  • GAMMA_ONLY_SIGMA
  • IC_CORR_LIST
  • IC_CORR_LIST_BETA
  • IMAGE_CHARGE_MODEL
  • NPARAM_PADE
  • NUMB_POLES
  • OMEGA_MAX_FIT
  • PERIODIC
  • PRINT_EXX
  • RI_SIGMA_X
  • SC_GW0_ITER
  • UPDATE_XC_ENERGY

• Keyword descriptions

  SECTION_PARAMETERS
  	&GW {Logical}
  	Activates cubic-scaling RPA, GW and Laplace-SOS-MP2 calculations.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  ANALYTIC_CONTINUATION
  	ANALYTIC_CONTINUATION {Keyword}
  	Defines which type of analytic continuation for the self energy is used
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: PADE
  	List of valid keywords: PADE Use Pade approximation. TWO_POLE Use 'two-pole' model.

  BSE
  	BSE {Logical}
  	If true, electronic excitation energies are computed from the Bethe-Salpeter equation on top of GW eigenvalues. Parameter of BSE can be adjusted in the corresponding section.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  CORR_MOS_OCC
  	CORR_MOS_OCC {Integer}
  	Number of occupied MOs whose energies are corrected by RI-G0W0. Counting beginning from HOMO, e.g. 3 corrected occ. MOs correspond to correction of HOMO, HOMO-1 and HOMO-2. Numerical effort and storage of RI-G0W0 increase linearly with this number. In case you want to correct all occ. MOs, insert a number larger than the number of occ. MOs.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 10
  	Alias names for this keyword: CORR_OCC

  CORR_MOS_VIRT
  	CORR_MOS_VIRT {Integer}
  	Number of virtual MOs whose energies are corrected by RI-G0W0. Counting beginning from LUMO, e.g. 3 corrected occ. MOs correspond to correction of LUMO, LUMO+1 and LUMO+2. Numerical effort and storage of RI-G0W0 increase linearly with this number. In case you want to correct all virt. MOs, insert a number larger than the number of virt. MOs.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 10
  	Alias names for this keyword: CORR_VIRT

  CROSSING_SEARCH
  	CROSSING_SEARCH {Keyword}
  	Determines, how the self_energy is evaluated on the real axis.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: NEWTON
  	List of valid keywords: BISECTION Make a bisection fix point iteration. NEWTON Make a Newton-Raphson fix point iteration. Z_SHOT Calculate the derivative of Sigma and out of it Z. Then extrapolate using Z.

  EPS_ITER
  	EPS_ITER {Real}
  	Target accuracy for the eigenvalue self-consistency. If the G0W0 HOMO-LUMO gap differs by less than the target accuracy during the iteration, the eigenvalue self-consistency cycle stops. Unit: Hartree.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 1.36000000E-003
  	Default unit: [eV]

  EV_GW_ITER
  	EV_GW_ITER {Integer}
  	Maximum number of iterations for eigenvalue self-consistency cycle. The computational effort of GW scales linearly with this number.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 1

  FERMI_LEVEL_OFFSET
  	FERMI_LEVEL_OFFSET {Real}
  	Fermi level for occ. orbitals: e_HOMO + FERMI_LEVEL_OFFSET; Fermi level for virt. orbitals: e_LUMO - FERMI_LEVEL_OFFSET. In case e_homo + FERMI_LEVEL_OFFSET < e_lumo - FERMI_LEVEL_OFFSET, we set Fermi level = (e_HOMO+e_LUMO)/2. For cubic-scaling GW, the Fermi level is always equal to (e_HOMO+e_LUMO)/2 regardless of FERMI_LEVEL_OFFSET.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 2.00000000E-002

  GAMMA_ONLY_SIGMA
  	GAMMA_ONLY_SIGMA {Logical}
  	If true, the correlation self-energy is only computed at the Gamma point. The Gamma point itself is obtained by averaging over all kpoints of the DFT mesh.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.
  	Alias names for this keyword: GAMMA

  IC_CORR_LIST
  	IC_CORR_LIST {Real} ... or a range {Real}..{Real}
  	List of image charge correction from a previous calculation to be applied in G0W0 or evGW. Keyword is active, if the first entry is positive (since IC corrections are positive occupied MOs. The start corresponds to the first corrected GW level.
  	This keyword cannot be repeated and it expects a list of reals.
  	Default value: -2.72113839E+001
  	Default unit: [eV]

  IC_CORR_LIST_BETA
  	IC_CORR_LIST_BETA {Real} ... or a range {Real}..{Real}
  	IC_CORR_LIST for beta spins in case of open shell calculation.
  	This keyword cannot be repeated and it expects a list of reals.
  	Default value: -2.72113839E+001
  	Default unit: [eV]

  IMAGE_CHARGE_MODEL
  	IMAGE_CHARGE_MODEL {Logical}
  	If true, an image charge model is applied to mimic the renormalization of electronic levels of a molecule at a metallic surface. For this calculation, the molecule has to be reflected on the desired xy image plane. The coordinates of the reflected molecule have to be added to the coord file as ghost atoms. For the ghost atoms, identical basis sets the normal atoms have to be used.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.
  	Alias names for this keyword: IC

  NPARAM_PADE
  	NPARAM_PADE {Integer}
  	Number of parameters for the Pade approximation when using the latter for the analytic continuation of the self energy. 16 parameters (corresponding to 8 poles) are are recommended.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 16

  NUMB_POLES
  	NUMB_POLES {Integer}
  	Number of poles for the fitting. Usually, two poles are sufficient.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 2

  OMEGA_MAX_FIT
  	OMEGA_MAX_FIT {Real}
  	Determines fitting range for the self-energy on the imaginary axis: [0, OMEGA_MAX_FIT] for virt orbitals, [-OMEGA_MAX_FIT,0] for occ orbitals. Unit: Hartree. Default: 0.734996 H = 20 eV.
  	This keyword cannot be repeated and it expects precisely one real.
  	Default value: 7.34996000E-001

  PERIODIC
  	PERIODIC {Logical}
  	If true, the periodic correction scheme is used employing k-points.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.

  PRINT_EXX
  	PRINT_EXX {Keyword}
  	Print exchange self-energy minus exchange correlation potential for Gamma-only calculation (PRINT). For a GW calculation with k-points we use this output as exchange self-energy (READ). This is a temporary solution because the hybrid MPI/OMP parallelization in the HFX by Manuel Guidon conflicts with the parallelization in low-scaling GW k-points which is most efficient with maximum number of MPI tasks and minimum number of OMP threads. For HFX by M. Guidon, the density matrix is fully replicated on every MPI rank which necessitates a high number of OMP threads per MPI rank for large systems to prevent out of memory. Such a high number of OMP threads would slow down the GW calculation severely. Therefore, it was decided to temporarily divide the GW k-point calculation in a Gamma-only HF calculation with high number of OMP threads to prevent out of memory and a GW k-point calculation with 1 OMP thread per MPI rank reading the previousHF output.
  	This keyword cannot be repeated and it expects precisely one keyword.
  	Default value: FALSE
  	List of valid keywords: FALSE FALSE is needed if you want to do nothing here. READ Please, put READ for the k-point GW calculation to read the exact exchange. You have to provide an output file including the exact exchange. This file has to be named 'exx.dat'. SKIP_FOR_REGTEST SKIP_FOR_REGTEST is only used for the GW k-point regtest where no exchange self-energy is computed. TRUE Please, put TRUE for Gamma only calculation to get the exchange self-energy. If 'SIGMA_X' and the corresponding values for the exchange-energy are written, the writing has been successful

  RI_SIGMA_X
  	RI_SIGMA_X {Logical}
  	If true, the exchange self-energy is calculated approximatively with RI. This is only recommended in case exact exchange is very costly, e.g. when using diffuse basis functions (seems not to work for periodic systems).
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .TRUE.

  SC_GW0_ITER
  	SC_GW0_ITER {Integer}
  	Maximum number of iterations for GW0 self-consistency cycle. The computational effort of GW is not much affected by the number of scGW0 cycles.
  	This keyword cannot be repeated and it expects precisely one integer.
  	Default value: 1

  UPDATE_XC_ENERGY
  	UPDATE_XC_ENERGY {Logical}
  	If true, the Hartree-Fock and RPA total energy are printed and the total energy is corrected using exact exchange and the RPA correlation energy.
  	This keyword cannot be repeated and it expects precisely one logical.
  	The lone keyword behaves as a switch to .TRUE.
  	Default value: .FALSE.