Variables
This page gives a brief explanation of the format and meaning for input variables used by Yambo. Check the Units and Format pages for accepted values of each.
All Variables (alphabetical order)
BDmRange BEnRange BEnSteps BLongDir BndsRnXd BndsRnXp BoseCut BoseTemp BS_CPU BS_nCPU_LinAlg_DIAGO
BS_nCPU_LinAlg_INV BS_ROLEs bse BSEBands BSEEhEny BSEmod BSENGBlk BSENGexx BSEPSInvTrs BSHayTrs
bsk BSKmod BSSInvMode BSSInvPFratio BSSmod CGrdSpXd chi ChiLinAlgMod Chimod cohsex
CUTBox CUTCol_test CUTCylLen CUTGeo CUTRadius CUTwsGvec DbGdQsize DbGdQsize DBsFRAGpm DBsIOoff
DIP_Threads DipApproach DipApproach DipPDirect DipPDirect DmERefXd DmRngeXd DmRngeXp DrClassic DrudeWBS
DrudeWXd dScStep DysSolver EhEngyXd ElecTemp Em1Anys em1d em1s EMStpsXd EnRngeXd
EnRngeXp ETStpsXd ETStpsXp ExtendOut EXXRLvcs FFTGvecs Gauge GbndRnge GDamping GDmRnge
GEnRnge GEnSteps GfnQP_E GfnQP_N GfnQP_Wc GfnQP_Wc_dos GfnQP_Wc_E GfnQP_Wv GfnQP_Wv_dos GfnQP_Wv_E
GfnQP_Z GfnQPdb GrFnTpXd GTermEn GTermKind gw0 HF_and_locXC IDEm1Ref IkSigLim IkXLim
K_Threads KfnQP_E KfnQP_N KfnQP_Wc KfnQP_Wc_dos KfnQP_Wc_E KfnQP_Wv KfnQP_Wv_dos KfnQP_Wv_E KfnQP_Z
KfnQPdb LifeTrCG LongDrXd LongDrXp LRC_alpha MaxGvecs MEM_tresh MetDamp Nelectro NewtDchk
NGBlkXd NLogCPUs NoCondSumRule NonPDirs OccTresh OnMassShell optics PAR_def_mode PAR_def_mode PPAPntXp
Qdirection QPerange QPerange QpgFull QPkrange QPkrange QpntsRXd QptCoord QShiftOrder RandGvec
RandQpts Reflectivity rim_cut SE_CPU SE_ROLEs SE_Threads setup ShiftedPaths ShiftedPaths StdoHash
UseNLCC VXCRLvcs WehCpl WFbuffIO X_finite_q_CPU X_finite_q_nCPU_LinAlg_INV X_finite_q_ROLEs X_q_0_CPU X_q_0_nCPU_LinAlg_INV X_q_0_ROLEs
X_Threads XfnQP_E XfnQP_N XfnQP_Wc XfnQP_Wc_dos XfnQP_Wc_E XfnQP_Wv XfnQP_Wv_dos XfnQP_Wv_E XfnQP_Z
XfnQPdb
Global options
DBsIOoff(Units: , Format: String)
- Meaning: List of databases not written to disk
- Tip: Space-separated list of DB with NO I/O. DB is (DIP,X,HF,COLLs,J,GF,CARRIERs,OBS,W,SC,BS,ALL)
- Meaning: List of databases not written to disk
DBsFRAGpm(Units: , Format: String)
- Meaning: List of databases to be fragmented
- Tip: Space-separated list of +DB to FRAG and -DB to NOT FRAG, where DB is (DIP,X,W,HF,COLLS,K,BS,QINDX,RT,ELP
- Meaning: List of databases to be fragmented
FFTGvecs(Units: RL/Energy, Format: Integer/Real)
- Meaning: Number of G-vectors or energy cut off for expanding the wavefunctions/FFT transforms
- Tip: It needs careful convergence. Determines the memory needed.
- Meaning: Number of G-vectors or energy cut off for expanding the wavefunctions/FFT transforms
Initialization
MaxGvecs(Units: RL/Energy, Format: Integer/Real)
- Meaning: Maximum number of G-vectors that can be used by code
- Tip:
- Meaning: Maximum number of G-vectors that can be used by code
Random integration method and cutoff
RandQpts(Units: RL, Format: Integer)
- Meaning: Number of random q-points in the BZ
- Tip: It needs convergence: values like 10^6 can be used to ensure convergence.
- Meaning: Number of random q-points in the BZ
CUTGeo(Units: None, Format: String)
- Meaning: Cutoff geometry
- Tip: Allowed values are: "box/cylinder/sphere X/Y/Z/XY...", e.g. "box xy" or "cylinder y".
- Meaning: Cutoff geometry
Hartree-Fock Self-energy and Vxc
EXXRLvcs(Units: RL/Energy, Format: Integer/Real)
- Meaning: Number of G-vectors used in the sum of the exchange self-energy Sx.
- Tip: It needs careful convergence: not particularly time consuming, large values can be used to ensure convergence.
- Meaning: Number of G-vectors used in the sum of the exchange self-energy Sx.
GW
QPkrange(Units: None, Format: Range)
- Meaning: First and last Indexes of kpoints and bands the self energy correction is calculated
- Tip: If interested in non consecutive kpoints or bands multiple rows can be also considered
- Meaning: First and last Indexes of kpoints and bands the self energy correction is calculated
GbndRnge(Units: None, Format: Range)
- Meaning: Bands range: Specifies the number of bands entering in the sum over states in the correlation part of the self energy
- Tip: It needs several empty states. Single quasiparticle states converges very slowly with respect GbndRnge, energy differences (e.g. gaps) behave better. See also GTermKind variable in order to speed up the convergences.
- Meaning: Bands range: Specifies the number of bands entering in the sum over states in the correlation part of the self energy
GfnQPdb(Units: None, Format: String)
- Meaning: Database for QP corrections.
- Tip: From a previous GW calculation. An interpolation of the missing QP-values on the basis of the QP-database is available. To be used for a GW self consistent calcuation.
- Meaning: Database for QP corrections.
GTermKind(Units: None, Format: String)
- Meaning: Type of terminator to accelarate onvergence with respect empty states
- Tip: Default is "none", possible options are "BG" for the Bruneval-Gonze terminator. See BG[1]
- Meaning: Type of terminator to accelarate onvergence with respect empty states
ExtendOut(Units: None, Format: Flag)
- Meaning: Extended output: Print more quantities in qp output files
- Tip: Optional variable (-V qp). Uncomment to activate
- Meaning: Extended output: Print more quantities in qp output files
Screening
NGBlkXd(Units: RL/Energy, Format: Integer/Real)
- Meaning: Number of G-vectors or energy cut off in the screening.
- Tip: Determines the size of the dielectric matrix in G-space. Needed for inclusion of local field effects, it should be much smaller than the number of G-vectors needed to expand the wavefunctions. It needs careful convergence.
- Meaning: Number of G-vectors or energy cut off in the screening.
PPAPntXp(Units: Energy, Format: Real)
- Meaning: Plasmon pole Imaginary Energy (Default 1 Ha)
- Tip: The self energy in the imaginary axis should be a smooth function so it should not have a strong dependence on this pole energy. Set it at an higher value of the plasmon energy (see EELS spectrum)
- Meaning: Plasmon pole Imaginary Energy (Default 1 Ha)
Optics/chi in G-space
Chimod(Units: None, Format: String)
- Meaning: Type of kernel in TDDFT Dyson equation
- Tip: Do not set this manually - set using the appropriate -k command line option. Allowed values: IP/Hartree/ALDA/LRC/BSfxc. IP indicates no kernel (independent particle level/RPA without local fields)
- Meaning: Type of kernel in TDDFT Dyson equation
QpntsRXd(Units: None, Format: Range)
- Meaning: Range of indexes of q-points/transferred momenta to be computed.
- Tip: Set to 1 1 to select just the long wavelength term.
- Meaning: Range of indexes of q-points/transferred momenta to be computed.
BndsRnXd(Units: None, Format: Range)
- Meaning: Bands range: Specifies the number of bands entering in the sum over states in the RPA response function
- Tip: It needs several empty states. See also GTermKind variable in order to speed up the convergences.
- Meaning: Bands range: Specifies the number of bands entering in the sum over states in the RPA response function
EnRngeXd(Units: Energy, Format: Range)
- Meaning: Energy range the spectrum is calculated across.
- Tip: Extremae of the energy range across which optical spectra will be computed.
- Meaning: Energy range the spectrum is calculated across.
DmRngeXd(Units: Energy, Format: Range)
- Meaning: Determines the damping used across the requested spectral range.
- Tip: Typically this is kept constant. If different values are used, the damping at each energy will be interpolated linearly. This can be useful when poor k-point sampling leads to large oscillations at higher energy.
- Meaning: Determines the damping used across the requested spectral range.
ETStpsXd(Units: None, Format: Integer)
- Meaning: Number of energy steps in computing X
- Tip: Determines the number of steps in energy the response function/spectrum is computed for in the desired range defined by EnRngeXd. In the case of a full frequency GW the range is fixed by the occupied/empty states included in the calculation, the number of frequency requires a careful check
- Meaning: Number of energy steps in computing X
LongDrXd(Units: Length, Format: Vector)
- Meaning: Electric field direction
- Tip: Pay attention how the system is oriented when treating non 3D systems and choose a direction in the plane/axis where your system lies
- Meaning: Electric field direction
Optics/BSE in eh-space
BSEBands(Units: None, Format: Range)
- Meaning: Bands range: Specifies the band states from which the electron-hole basis of the BSE kernel is constructed
- Tip: Choose few bands close to the Fermi level.
- Meaning: Bands range: Specifies the band states from which the electron-hole basis of the BSE kernel is constructed
KfnQPdb(Units: None, Format: String)
- Meaning: Database for QP corrections.
- Tip: From a previous GW calculation. An interpolation of the missing QP-values on the basis of the QP-database is available
- Meaning: Database for QP corrections.
KfnQP_E(Units: eV/None/None, Format: Scissors)
- Meaning: QP corrections using a scissor operator and stretching coefficients for the conduction/valence bandwidths.
- Tip: From a previous GW calculation or experiment.
- Meaning: QP corrections using a scissor operator and stretching coefficients for the conduction/valence bandwidths.
Bethe Salpeter/TDDFT Kernel
BSENGexx(Units: RL/Energy, Format: Integer/Real)
- Meaning: G-components to be summed in the Exchange part of the BSE kernel, which takes into account the Local-field effects
- Tip: Small values increase speed. Convergence tests are required.
- Meaning: G-components to be summed in the Exchange part of the BSE kernel, which takes into account the Local-field effects
BSENGBlk(Units: RL/Energy, Format: Integer/Real)
- Meaning: Number of RL-components of the Screened Coulomb Potential matrix W(G,G'), to be included in the sum of the e-h attractive Kernel
- Tip: Try using the diagonal terms only first (BSresKmod BScplKmod variables); use a smaller number than the dimension of the Screened interaction matrix
- Meaning: Number of RL-components of the Screened Coulomb Potential matrix W(G,G'), to be included in the sum of the e-h attractive Kernel