Perform a time-dependent DFT calculation to obtain real and imaginary parts of frequency-dependent dielectric function.
Response
nfreq 5
strtfr 0.0
endfr 0.01
cnvi 0.001
cnvj 0.001
ebndtl 0.001
ifxc 0
isz 0
iyxc 0
End
Omitting the specific options in the Response block will cause default setting to be used during the calculation, as given above.
nfreq the number of frequencies in a.u. for which a TDDFT calculation is performed when calculating the dielectric function εe(ω) of a system (default=5).
strtfr is the start frequency in a.u. of the frequency range over which the dielectric function is calculated (default=0d0).
endfr is the end frequency in a.u. of the frequency range over which the dielectric function is calculated (default=1d-2).
cnvi the first convergence criterion for the change in the fitcoefficients for the fitfunctions, when fitting the density (default=1d-3).
cnvj the second convergence criterion for the change in the fitcoefficients for the fitfunctions, when fitting the density (default=1d-3).
ebndtl the energy band tolerance, for determination which routines to use for calculating the numerical integration weights, when the energy band posses no or to less dispersion (default=1d-3).
ifxc integer indicating
which fxc kernel is used (default=0).
0 = Adiabatic Local Density Approximation (ALDA) (Can. J. Phys. 58,
1200 (1985)).
1 = Gross-Kohn, frequency dependent fxc kernel (PRL 55, 2850 (1985),
57, 923 (1986)),
2 = van Leeuwen-Baerends (LB94) (PRA 49, 2421 (1994)),
Only the default option for ifxc is implemented at the moment.
isz integer indicating
whether or not scalar zeroth order relativistic effects are
included in the TDDFT calculation (default=0).
0 = relativistic effects are not included,
1 = relativistic effects are included.
iyxc integer for
printing yxc-tensor (default=0) (JCP 115, 1995 (2001)).
0 = not printed,
1 = printed
static An alternative method that allows an analytic evaluation of the static response (Normally the static component is approximated by a finite small value). This option should only be used only for (non relativistic calculations on) insulators, and it has no effect on metals. Experience shows that KSPACE convergence can be slower, and this is why it is not the default.
newvk Use the slightly modified version of the VK kernel (Phys. Rev. B 74, 245117). When using this option one uses effectively the >static option, even for metals, so one should check carefully the convergence with the KSPACE parameter. An example response block for a vignale kohn calculation looks like
Response
nfreq 2
strtfr 0.10d0
endfr 0.25d0
newvk
iyxc 1
cnt
END
qv/cnt Use the QV or CNT parametrization for the longitudinal and transverse kernels of the xc-kernel of the homogeneous electron gas. Use this in conjunction with the newvk option. (Refs: PRB 65, 235121 (QV); J. Phys. Condens. Matter 9, L475 (CNT))
