6.1. ANPHON: Input files
Format of input files
Each input file should consist of entry fields. Available entry fields are
&general, &cell, &scph, &qha, &relax, &kpoint, &strain, and &displace.
The format of the input file is the same as that of alm which can be found here.
List of supported input variables
&general |
|||
&scph |
|||
&qha |
|||
&relax |
|||
&analysis |
|||
Description of input variables
“&general”-field
PREFIX-tag : Job prefix to be used for names of output files
- Default:
None
- Type:
String
MODE-tag = phonons | RTA
phonons
Calculate phonon dispersion relation, phonon DOS,Grüneisen parameters etc.RTA
Calculate phonon lifetimes and lattice thermal conductivitybased on the Boltzmann transport equation (BTE)with the relaxation time approximation (RTA).SCPH
Calculate temperature dependent phonon dispersion curvesby the self-consistent phonon method.
- Default:
None
- Type:
String
NKD-tag : Number of atomic species
- Default:
None
- Type:
Integer
KD-tag = Name[1], … , Name[
NKD
]
- Default:
None
- Type:
Array of strings
- Example:
In the case of GaAs with
NKD = 2
, it should beKD = Ga As
.
MASS-tag = mass[1], … , mass[
NKD
]
- Default:
Standard atomic weight of elements given by the
KD
-tag- Type:
Array of double
- Example:
In the case of Bi_{2}Te_{3} with
NKD = 2
,MASS
should beMASS = 208.98 127.60
.
FCSXML-tag : XML file containing force constants generated by the program alm
- Default:
None
- Type:
String
FC2XML-tag : XML file containing harmonic force constants for different size of supercell
- Default:
None
- Type:
String
- Description:
When
FC2XML
is given, the harmonic force constants in this file are used for calculating dynamical matrices. It is possible to use different size of supercell for harmonic and anharmonic terms, which are specified byFC2XML
andFCSXML
respectively.
TOLERANCE-tag : Tolerance for finding symmetry operations
- Default:
1.0e-6
- Type:
Double
PRINTSYM-tag = 0 | 1
0
Symmetry operations won’t be saved in “SYMM_INFO_PRIM”
1
Symmetry operations will be saved in “SYMM_INFO_PRIM”
- Default:
0
- type:
Integer
NONANALYTIC-tag = 0 | 1 | 2 | 3
0
Non-analytic correction is not considered.1
Include the non-analytic correction by the damping method proposed by Parlinski.2
Include the non-analytic correction by the mixed-space approach3
Include the non-analytic correction by the Ewald method
- Default:
0
- Type:
Integer
- Description:
When
NONANALYTIC > 0
, appropriateBORNINFO
needs to be given. IfNONANALYTIC = 1
, one may need to adjust theNA_SIGMA
value to obtain reasonably smooth dispersion curves.
NA_SIGMA-tag : Damping factor for the non-analytic term
- Default:
0.0
- Type:
Double
- Description:
Used when
NONANALYTIC = 1
. The definition ofNA_SIGMA
is described in the formalism section.
BORNINFO-tag : File containing the macroscopic dielectric tensor and Born effective charges for the non-analytic correction
- Default:
None
- Type:
String
- Description:
The details of the file format can be found here.
BORNSYM-tag = 0 | 1
0
Do not symmetrize Born effective charges
1
Symmetrize Born effective charges by using point group symmetry
- Default:
0
- Type:
Integer
TMIN, TMAX, DT-tags : Temperature range and its stride in units of Kelvin
- Default:
TMIN = 0
,TMAX = 1000
,DT = 10
- Type:
Double
EMIN, EMAX, DELTA_E-tags : Energy range and its stride in units of kayser (cm^{-1})
- Default:
EMIN
andEMAX
are set automatically from the eigenfrequencies as of ver. 1.5.0. The default value forDELTA_E
is 10.0.- Type:
Double
ISMEAR-tag = -1 | 0 | 1
-1
Tetrahedron method
0
Lorentzian smearing with width of
EPSILON
1
Gaussian smearing with width of
EPSILON
- Default:
-1
- Type:
Integer
- Description:
ISMEAR
specifies the method for Brillouin zone integration
EPSILON-tag : Smearing width in units of Kayser (cm^{-1})
- Default:
10.0
- Type:
Double
- Description:
This variable is neglected when
ISMEAR = -1
BCONNECT-tag = 0 | 1 | 2
0
Phonon band is saved without change (sorted in order of energy)1
Phonon band is connected by using the similarity of eigenvectors.2
Same asBCONNECT=1
. In addition, information about the connectivity issaved asPREFIX.connection
.
- Default:
0
- Type:
Integer
- Description:
The algorithm for connecting a band structure is described here.
CLASSICAL-tag = 0 | 1
0
Use quantum statistics (default)
1
Use classical statistics
- Default:
0
- Type:
Integer
- Description:
When
CLASSICAL = 1
, all thermodynamic functions including the occupation function, heat capacity, and mean square displacements are calculated using the classical formulae. This option may be useful when comparing the lattice dynamics and molecular dynamics results.
Function
Quantum (
CLASSICAL = 0
)Classical (
CLASSICAL = 1
)Occupation number
\(\displaystyle n_\mathrm{B}=\frac{1}{\exp(\beta\hbar\omega) - 1}\)
\(\displaystyle n_\mathrm{C}=\frac{1}{\beta\hbar\omega}\)
Mode specific heat
\(\displaystyle c_{q} = k_{\mathrm{B}}\left[\frac{\beta\hbar\omega_q}{2}\mathrm{csch}\bigg({\frac{\beta\hbar\omega_q}{2}}\bigg)\right]^2\)
\(\displaystyle c_{q} = k_{\mathrm{B}}\)
MSD of normal mode \(\braket{Q^{*}_qQ_q}\)
\(\displaystyle \frac{\hbar (1 + n_{\mathrm{B}})}{2\omega_q}\)
\(\displaystyle \frac{1}{\beta\omega_{q}^{2}}\)
TRISYM-tag : Flag to use symmetry operations to reduce the number of triples of \(k\) points for self-energy calculations
0
Symmetry will not be used
1
Use symmetry to reduce triples of \(k\) points
- Default:
1
- Type:
Integer
- Description:
This variable is used only when
MODE = RTA
.Note
TRISYM = 1
can reduce the computational cost, but phonon linewidth stored to the filePREFIX
.result needs to be averaged at points of degeneracy. For that purpose, a subsidiary program analyze_phonons.py* should be used.
RESTART-tag : Flag to restart the calculation when
MODE = RTA
0
Calculate from scratch
1
Restart from the existing file
- Default:
1 if there is a file named
PREFIX
.result; 0 otherwise- Type:
Integer
“&scph”-field (Read only when MODE = SCPH
)
KMESH_INTERPOLATE-tag = k1, k2, k3
- Default:
None
- Type:
Array of integers
- Description:
In the iteration process of the SCPH equation, the interpolation is done using the \(k\) mesh defined by
KMESH_INTERPOLATE
.
KMESH_SCPH-tag = k1, k2, k3
- Default:
None
- Type:
Array of integers
- Description:
This \(k\) mesh is used for the inner loop of the SCPH equation. Each value of
KMESH_SCPH
must be equal to or a multiple of the number ofKMESH_INTERPOLATE
in the same direction.
SELF_OFFDIAG-tag = 0 | 1
0
Neglect the off-diagonal elements of the loop diagram in the SCPH calculation
1
Consider the off-diagonal elements of the loop diagram in the SCPH calculation
- Default:
0
- Type:
Integer
- Description:
SELF_OFFDIAG = 1
is more accurate, but expensive.
TOL_SCPH-tag: Stopping criterion of the SCPH iteration
- Default:
1.0e-10
- Type:
Double
- Description:
The SCPH iteration stops when both \([\frac{1}{N_{q}}\sum_{q} (\Omega_{q}^{(i)}-\Omega_{q}^{(i-1)})^{2}]^{1/2}\) <
TOL_SCPH
and \((\Omega_{q}^{(i)})^{2} \geq 0 \; (\forall q)\) are satisfied. Here, \(\Omega_{q}^{(i)}\) is the anharmonic phonon frequency in the \(i\)th iteration and \(q\) is the phonon modes at the irreducible momentum grid ofKMESH_INTERPOLATE
.
MIXALPHA-tag: Mixing parameter used in the SCPH iteration
- Default:
0.1
- Type:
Double
MAXITER-tag: Maximum number of the SCPH iteration
- Default:
1000
- Type:
Integer
LOWER_TEMP-tag = 0 | 1
0
The SCPH iteration start from
TMIN
toTMAX
. (Raise the temperature)1
The SCPH iteration start from
TMAX
toTMIN
. (Lower the temperature)
- Default:
1
- Type:
Integer
WARMSTART-tag = 0 | 1
0
SCPH iteration is initialized by harmonic frequencies and eigenvectors
1
SCPH iteration is initialized by the solution of the previous temperature
- Default:
1
- Type:
Integer
- Description:
WARMSTART = 1
usually improves the convergence.
IALGO-tag = 0 | 1
0
MPI parallelization for the \(k\) point
1
MPI parallelization for the phonon branch
- Default:
0
- Type:
Integer
- Description:
Use
IALGO = 1
when the primitive cell contains many atoms and the number of \(k\) points is small.
RESTART_SCPH-tag = 0 | 1
0
Perform a SCPH calculation from scratch
1
Skip a SCPH iteration by loading a precalculated result
- Default:
1 if the file
PREFIX.scph_dymat
exists in the working directory; 0 otherwise- Type:
Integer
BUBBLE-tag = 0 | 1
0
No bubble correction to the dynamical matrix
1
Calculate bubble correction on top of the SCPH dynamical matrix
- Default:
0
- Type:
Integer
RELAX_STR-tag = 0 | 1 | 2 | 3
0
Don’t relax the crystal structure (not supported when
mode = QHA
).1
Relax atomic positions.
2
Relax both atomic positions and the shape of the unit cell.
3
Lowest-order perturbation theory (not supported when
MODE = SCPH
).
- Default:
0
- Type:
Integer
“&qha”-field (Read only when MODE = QHA
)
KMESH_INTERPOLATE-tag = k1, k2, k3
- Default:
None
- Type:
Array of integers
- Description:
In the structural optimization based on quasiharmonic approximation (QHA), the interpolation is done using the \(k\) mesh defined by
KMESH_INTERPOLATE
.
KMESH_QHA-tag = k1, k2, k3
- Default:
None
- Type:
Array of integers
- Description:
This \(k\) mesh is used for the QHA-based structural optimization. Each value of
KMESH_QHA
must be equal to or a multiple of the number ofKMESH_INTERPOLATE
in the same direction.
RELAX_STR-tag = 0 | 1 | 2 | 3
0
Don’t relax the crystal structure (not supported when
mode = QHA
).1
Relax atomic positions.
2
Relax both atomic positions and the shape of the unit cell.
3
Lowest-order perturbation theory (not supported when
mode = SCPH
).
- Default:
0
- Type:
Integer
LOWER_TEMP-tag = 0 | 1
0
The structural optimization start from
TMIN
toTMAX
. (Raise the temperature)1
The structural optimization start from
TMAX
toTMIN
. (Lower the temperature)
- Default:
1
- Type:
Integer
QHA_SCHEME-tag = 0 | 1 | 2
0
Full optimization within QHA.
1
zero-static internal stress approximation (ZSISA).
2
volumetric ZSISA (v-ZSISA).
- Default:
0
- Type:
Integer
- Description:
This option is used only when
mode = QHA
andRELAX_STR = 2
.
“&relax”-field (Read only when RELAX_STR != 0
)
RELAX_ALGO-tag = 1 | 2
1
Steepest decent (not recommended)
2
Newton-like method
- Default:
2
- Type:
Integer
- Description:
Algorithm to update the crystal structure in structural optimization. This option is used only when
RELAX_STR = 1, 2
.RELAX_ALGO = 1
works properly only when the unit cell is fixed (RELAX_STR = 1
).
ALPHA_STDECENT-tag: Coefficient of steepest decent in structural optimization
- Default:
1.0e4
- Type:
Double
- Description:
\(\alpha\) coefficient in structural optimization with steepest-decent algorithm. The unit is [\(m_e a_B^2/(2\text{Ry})\)]. This option is used only when
RELAX_ALGO = 1
.
MAX_STR_ITER-tag: Maximum number of structure updates.
- Default:
100
- Type:
Integer
- Description:
This option is used only when
RELAX_STR = 1, 2
.
ADD_HESS_DIAG-tag: Correction to the estimated Hessian of free energy in units of kayser (cm^{-1})
- Default:
100.0
- Type:
Double
- Description:
The squared
ADD_HESS_DIAG
is added to the diagonal components of estimated Hessians, which is used to update crystal structures in structural optimization.ADD_HESS_DIAG
makes the calculation more robust in the presence of soft modes near the structural phase transition, but setting large values will make the convergence slower. This option is used only whenRELAX_ALGO = 2
.
COORD_CONV_TOL-tag: Threshold of convergence for atomic positions in structural optimization.
- Default:
1.0e-5
- Type:
Double
- Description:
The value is interpreted in units of Bohr. This option is used only when
RELAX_STR = 1, 2
.
MIXBETA_COORD-tag: Mixing coefficient for atomic positions in structure updates.
- Default:
0.5
- Type:
Double
- Description:
This option is used only when
RELAX_STR = 1, 2
.
CELL_CONV_TOL-tag: Threshold of convergence for displacement gradient tensor \(u_{\mu \nu}\) in structural optimization.
- Default:
1.0e-5
- Type:
Double
- Description:
This option is used only when
RELAX_STR = 2
.
MIXBETA_CELL-tag: Mixing coefficient for displacement gradient tensor \(u_{\mu \nu}\) in structure updates.
- Default:
0.5
- Type:
Double
- Description:
This option is used only when
RELAX_STR = 2
.
SET_INIT_STR-tag = 1 | 2 | 3
1
Set initial structure from the input file at each temperature.
2
Start from the crystal structure of the previous temperature.
3
Start from the crystal structure of the previous temperature in low-symmetry phase.
- Default:
1
- Type:
Integer
- Description:
This option specifies how to set the initial structure of structural optimization at different temperatures. This option is used when
RELAX_STR = 1, 2
. In all options, the initial structure at the initial temperature is set from the input file. The initial structure of the input file is read from the&strain
and&displace
field. WhenSET_INIT_STR = 3
, the initial displacement from the input file is used if the crystal structure converges to the high-symmetry phase in the previous temperature. The criteria to distinguish low-symmetry and high-symmetry phases is explained in COOLING_U0_THR.
COOLING_U0_INDEX-tag = 0 | 1 | … | 3N-1 (N : the number of atoms in the unit cell)
- Default:
0
- Type:
Integer
- Description:
Specify as \(3\times\alpha + \mu\). Here, \(\alpha\) denotes the atom index in the primitive cell and \(\mu\) is the xyz index, where both indices are zero-indexed. See the description of COOLING_U0_THR for details. This option is used only when
SET_INIT_STR = 3
.
COOLING_U0_THR-tag: Threshold to judge high-symmetry phase in structural optimization [Bohr].
- Default:
0.001
- Type:
Double
- Description:
The crystal structure is judged to be back to the high-symmetry phase if \(u^{(0)}\) [
COOLING_U0_INDEX
] <COOLING_U0_THR
. This option is useful in cooling calculations because small displacements to the high-symmetry structure is required to induce spontaneous symmetry breaking. This option is used only whenSET_INIT_STR = 3
.
STAT_PRESSURE-tag: Hydrostatic pressure in GPa.
- Default:
0.0
- Type:
Double
RENORM_2TO1ST-tag = 0 | 1 | 2
0
Set zero.
1
Real-space IFC renormalization. (not recommended)
2
Finite difference method with respect to strain.
- Default:
2
- Type:
Integer
- Description:
This option specifies the method to calculate first-order derivatives of first-order IFCs with respect to strain
\(\frac{\partial \Phi_{\mu}(0\alpha)}{\partial u_{\mu_1 \nu_1} }\).
This option is used only when
RELAX_STR = 2, 3
. Note thatRENORM_2TO1ST = 1
requires rotational invariance on IFCs, which is not checked in the program ANPHON.RENORM_2TO1ST = 0
can be used for high-symmetry materials in which strain-force coupling is zero, which a user need to confirm themselves.
RENORM_34TO1ST-tag = 0 | 1
0
Set zero.
1
Real-space IFC renormalization.
- Default:
0
- Type:
Integer
- Description:
This option specifies the method to calculate second and higher-order derivatives of first-order IFCs with respect to strain.
\(\frac{\partial^2 \Phi_{\mu}(0\alpha)}{\partial u_{\mu_1 \nu_1} \partial u_{\mu_2 \nu_2}}\), \(\frac{\partial^3 \Phi_{\mu}(0\alpha)}{\partial u_{\mu_1 \nu_1} \partial u_{\mu_2 \nu_2} \partial u_{\mu_3 \nu_3}}\)
This option is used only when
RELAX_STR = 2, 3
. Note thatRENORM_34TO1ST = 1
requires rotational invariance on IFCs, which a user need to confirm themselves.
RENORM_3TO2ND-tag = 1 | 2 | 3
1
Real-space IFC renormalization.
2
Finite difference method (Read input from all six strain patterns).
3
Finite difference method (Read input from specified strain patterns).
- Default:
2
- Type:
Integer
- Description:
This option specifies the method to calculate first-order derivatives of harmonic IFCs with respect to strain.
\(\frac{\partial \Phi_{\mu_1 \mu_2}(0\alpha_1, R \alpha_2)}{\partial u_{\mu \nu}}\)
This option is used only when
RELAX_STR = 2, 3
. To useRENORM_3TO2ND = 3
, the entries of the rotation matrices of ALL the space-group operations must be either 0 or \(\pm\) 1 in Cartesian representation.
STRAIN_IFC_DIR-tag: Directory name of the inputs of strain-IFC couplings.
- Default:
None
- Type:
String
- Description:
When
RENORM_2TO1ST = 2 `` or ``RENORM_3TO2ND = 3
, the input files of the strain-IFC couplings must be given properly in this directory.
“&cell”-field
Please specify the cell parameters of the primitive cell as:
&cell
a
a11 a12 a13
a21 a22 a23
a31 a32 a33
/
The cell parameters are then given by \(\vec{a}_{1} = a \times (a_{11}, a_{12}, a_{13})\), \(\vec{a}_{2} = a \times (a_{21}, a_{22}, a_{23})\), and \(\vec{a}_{3} = a \times (a_{31}, a_{32}, a_{33})\).
Note
The lattice constant \(a\) must be consistent with the value used for the program alm. For example, if one used \(a = 20.4 a_{0}\) for a 2x2x2 supercell of Si, one should use \(a = 10.2 a_{0}\) here for the primitive cell.
“&kpoint”-field
This entry field is used to specify the list of \(k\) points to be calculated. The first entry KPMODE specifies the types of calculation which is followed by detailed entries.
KPMODE = 0 : Calculate phonon frequencies at given \(k\) points
For example, if one wants to calculate phonon frequencies at Gamma (0, 0, 0) and X (0, 1/2, 1/2) of an FCC crystal, the
&kpoint
entry should be written as&kpoint 0 0.000 0.000 0.000 0.000 0.500 0.500 /
KPMODE = 1 : Band dispersion calculation
For example, if one wants to calculate phonon dispersion relations along G-K-X-G-L of a FCC crystal, the
&kpoint
entry should be written as follows:&kpoint 1 G 0.000 0.000 0.000 K 0.375 0.375 0.750 51 K 0.375 0.375 0.750 X 0.500 0.500 1.000 51 X 0.000 0.500 0.500 G 0.000 0.000 0.000 51 G 0.000 0.000 0.000 L 0.500 0.500 0.500 51 /The 1st and 5th columns specify the character of Brillouin zone edges, which are followed by fractional coordinates of each point. The last column indicates the number of sampling points.
KPMODE = 2 : Uniform \(k\) grid for phonon DOS and thermal conductivity
In order to perform a calculation with 20x20x20 \(k\) grid, the entry should be
&kpoint 2 20 20 20 /
“&strain”-field (Read only when RELAX_STR = 2
)
Please specify the initial displacement gradient tensor \(u_{\mu \nu}\) for structural optimization as
&cell
u_xx u_xy u_xz
u_yx u_yy u_yz
u_zx u_zy u_zz
/
Note that a user need to give a symmetric matrix.
“&displace”-field (Read only when RELAX_STR = 1, 2
)
Please specify the initial atomic displacements \(u^{(0)}_{\alpha \mu}\) [Bohr].
DISPMODE = 0 : Fractional coordinate representation
The
&displace
entry should be written as follows. The first four lines after DISPMODE (= 0) specifies the unit cell, whose format is the same as the&cell
field. Note that the unit cell in the&displace
field is used only for transforming the input to the real space representation. Thus, the unit cell here does not need to be commensurate with the primitive cell or some supercells.u_ij is the j-th component of the displacement of i-th atom in the primitive cell in fractional coordinate representation.
&displace 0 a a11 a12 a13 a21 a22 a23 a31 a32 a33 u_01, u_02, u_03 ... /
DISPMODE = 1 : Cartesian coordinate representation
Each line after DISPMODE (= 1) specifies the initial atomic displacement in Cartesian representation. u_ij is the j component of the displacement of i-th atom in the primitive cell.
&displace 1 u_0x, u_0y, u_0z ... /
“&analysis”-field
GRUNEISEN-tag = 0 | 1
0
Grüneisen parameters will not be calculated
1
Grüneisen parameters will be stored
- Default:
0
- Type:
Integer
- Description:
When
MODE = phonons
andGRUNEISEN = 1
, Grüneisen parameters will be stored inPREFIX
.gru (KPMODE = 1) orPREFIX
.gru_all (KPMODE = 2).
Note
To compute Grüneisen parameters, cubic force constants must be contained in the FCSXML
file.
PRINTEVEC-tag = 0 | 1
0
Do not print phonon eigenvectors
1
Print phonon eigenvectors in the
PREFIX
.evec file
- Default:
0
- Type:
Integer
PRINTXSF-tag = 0 | 1
0
Do not save an AXSF file
1
Create an AXSF file
PREFIX
.axsf
- Default:
0
- Type:
Integer
- Description:
This is to visualize the direction of vibrational modes at gamma (0, 0, 0) by XCrySDen. This option is valid only when
MODE = phonons
.
PRINTVEL-tag = 0 | 1
0
Do not print group velocity
1
Store phonon velocities to a file
- Default:
0
- Type:
Integer
- Description:
When
MODE = phonons
andPRINTVEL = 1
, group velocities of phonons will be stored inPREFIX
.phvel (KPMODE = 1) orPREFIX
.phvel_all (KPMODE = 2).
PRINTMSD-tag = 0 | 1
0
Do not print mean-square-displacement (MSD) of atoms
1
Save MSD of atoms to the file
PREFIX
.mds
- Default:
0
- Type:
Integer
- Description:
This flag is available only when
MODE = phonons
and KPMODE = 2.
PDOS-tag = 0 | 1
0
Only the total DOS will be printed in
PREFIX
.dos1
Atom-projected phonon DOS will be stored in
PREFIX
.dos
- Default:
0
- Type:
Integer
- Description:
This flag is available only when
MODE = phonons
and KPMODE = 2.
TDOS-tag = 0 | 1
0
Do not compute two-phonon DOS
1
Two-phonon DOSs will be stored in
PREFIX
.tdos
- Default:
0
- Type:
Integer
- Description:
This flag is available only when
MODE = phonons
and KPMODE = 2.Note
Calculation of two-phonon DOS is computationally expensive.
SPS-tag = 0 | 1 | 2
0
Do not compute scattering phase space
1
Total and mode-decomposed scattering phase space involvingthe three-phonon processes will be stored inPREFIX
.sps2
Three-phonon scattering phase space with the Bose factor will be stored in
PREFIX
.sps_Bose
- Default:
0
- Type:
Integer
- Description:
This flag is available only when
MODE = phonons
and KPMODE = 2.
PRINTPR-tag = 0 | 1
0
Do not compute the (atomic) participation ratio
1
Compute participation ratio and atomic participation ratio, which will bestored inPREFIX
.pr andPREFIX
.apr respectively.
- Default:
0
- Type:
Integer
- Description:
This flag is available when
MODE = phonons
.
KAPPA_COHERENT-tag = 0 | 1 | 2
0
Do not compute the coherent component of thermal conductivity
1
Compute the coherent component of thermal conductivity and save it in
PREFIX
.kl_coherent.2
In addition to above (KAPPA_COHERENT = 1
), all elements of the coherent termare saved inPREFIX
.kc_elem.
- Default:
0
- Type:
Integer
- Description:
This flag is available when
MODE = RTA
. For the theoretical details, please see this page.Caution
Still experimental. Please check the validity of results carefully.
KAPPA_SPEC-tag = 0 | 1
0
Do not compute the thermal conductivity spectra
1
Compute the thermal conductivity spectra, which will be stored in
PREFIX
.kappa_spec .
- Default:
0
- Type:
Integer
- Description:
This flag is available when
MODE = RTA
.
ISOTOPE-tag = 0 | 1
0
Do not consider phonon-isotope scatterings
1
Consider phonon-isotope scatterings
2
Consider phonon-isotope scatterings as inISOTOPE = 1
andthe calculated selfenergy is stored inPREFIX
.gamma_isotope
- Default:
0
- Type:
Integer
- Description:
When
MODE = RTA
andISOTOPE = 1 or 2
, phonon scatterings due to isotopes will be considered perturbatively.ISOFACT
should be properly given.
ISOFACT-tag = isofact[1], … , isofact[
NKD
]
- Default:
Automatically calculated from the
KD
tag- Type:
Array of doubles
- Description:
Isotope factor is a dimensionless value defined by \(\sum_{i} f_{i} (1 - m_{i}/\bar{m})^{2}\). Here, \(f_{i}\) is the fraction of the \(i\)th isotope of an element having mass \(m_{i}\), and \(\bar{m}=\sum_{i}f_{i}m_{i}\) is the average mass, respectively. This quantity is equivalent to \(g_{2}\) appearing in the original paper by S. Tamura [Phys. Rev. B, 27, 858.].
UCORR-tag = 0 | 1
0
Do nothing
1
Compute the displacement-displacement correlation function.The result is stored inPREFIX
.ucorr
- Default:
0
- Type:
Integer
- Description:
The displacement-displacement correlation function involves two atoms. The first atom is located in the primitive cell at the center (shift1=[0,0,0]) and the second atom is located in the \(\ell'\) th cell. The translation vector to the \(\ell'\) th cell can be specified by the
SHIFT_UCORR
tag. This tag is effective only whenMODE = phonons
and KPMODE = 2
SHIFT_UCORR-tag = l1, l2, l3
- Default:
[0, 0, 0]
- Type:
Array of integers
- Description:
This tag specifies the translation vector used for computing the displacement-displacement (uu) correlation function. For example, if one wants to compute the uu correlation function between an atom 1 in the cell at the center and atom 2 in the neighboring cell at \(\boldsymbol{r}(\ell')=(1,0,0)\),
SHIFT_UCORR
should be set asSHIFT_UCORR = 1 0 0
.
ZMODE-tag = 0 | 1
0
Do nothing
1
Compute the mode effective charges of the zone-center phonons.The result is stored inPREFIX
.zmode
- Default:
0
- Type:
Integer
- Description:
When
MODE = phonons
andZMODE = 1
, the mode effective charges are computed for the phonon modes at the Gamma point and saved inPREFIX
.zmode. The unit of the mode effective charge is \(e \; \text{amu}^{-1/2}\).
ANIME-tag = k1, k2, k3
- Default:
None
- Type:
Array of doubles
- Description:
This tag is to animate vibrational mode. k1, k2, and k3 specify the momentum of phonon modes to animate, which should be given in units of the reciprocal lattice vector. For example,
ANIME = 0.0 0.0 0.5
will animate phonon modes at (0, 0, 1/2). WhenANIME
is given,ANIME_CELLSIZE
is also necessary. You can choose the format of animation files, either AXSF or XYZ, byANIME_FORMAT
tag.
ANIME_FRAMES-tag: The number of frames saved in animation files
- Default:
20
- Type:
Integer
ANIME_CELLSIZE-tag = L1, L2, L3
- Default:
None
- Type:
Array of integers
- Description:
This tag specifies the cell size for animation. L1, L2, and L3 should be large enough to be commensurate with the reciprocal point given by the
ANIME
tag.
ANIME_FORMAT = xsf | xyz
- Default:
xyz
- Type:
String
- Description:
When
ANIME_FORMAT = xsf
,PREFIX
.anime???.axsf files are created for XcrySDen. WhenANIME_FORMAT = xyz
,PREFIX
.anime???.xyz files are created for VMD (and any other supporting software such as Jmol).
Format of BORNINFO
When one wants to consider the LO-TO splitting near the \(\Gamma\) point, it is necessary to set NONANALYTIC > 0
and
provide BORNINFO
file containing dielectric tensor \(\epsilon^{\infty}\) and Born effective charge \(Z^{*}\).
In BORNINFO
file, the dielectric tensor should be written in first 3 lines which are followed by Born effective charge tensors
for each atom as the following.
Here, \(N_p\) is the number of atoms contained in the primitive cell.
Attention
Please pay attention to the order of Born effective charges.