#!/bin/sh

# This example demonstrates how to calculate the frequency-dependent dielectric
# function with the help of the NewResponse implementation for a two-dimensional
# system. (see NewResponse) Furthermore, the general setup to run the TD-CDFT
# section as a restart calculation is presented as well. This allows for
# splitting of the frequency range into several parts, which can then be
# calculated in separate calculation without the overhead of evaluating the
# groundstate properties for each of them! Hence, it is a trivial
# parallelization possibility.

# =========================
# MoS2 Monolayer .xyz file:
# =========================

cat << eor > MoS2_2D_1L.xyz
3 

S          0.00000000       0.00300000      -7.76123300
S          0.00000000       0.00000000      -4.53876700
Mo         1.58000000       0.91221300      -6.15000000
VEC1       3.16000000       0.00000000       0.00000000
VEC2       1.58000000       2.73664028       0.00000000

eor

# ===============================================
# Simple single point calculation (no properties)
# ===============================================

AMS_JOBNAME=MoS2 $AMSBIN/ams <<eor

Task SinglePoint

System
  GeometryFile MoS2_2D_1L.xyz
End

Engine Band 
  UseSymmetry False

  NumericalQuality good

  DEPENDENCY BASIS=1e-10

  Tails bas=1e-10

  KSpace
    Regular
      NumberOfPoints 5 5
    End
  End

  Basis
    Type DZP
    Core Large
  End

  Convergence
   Criterion 1E-8
  End
EndEngine

eor

# ===================================
# Restart and compute some properties 
# ===================================

# Caution!
# One has to make sure to use the same
# Symmetry/NumericalQuality/KSpace/Basis/ZORA/... options for the
# ground state calculation and for the restart calculation! Otherwise a normal
# ground state SCF optimization will be performed in the restart calculation.


AMS_JOBNAME=MoS2_restart $AMSBIN/ams <<eor

  Task SinglePoint

  System 
    GeometryFile MoS2_2D_1L.xyz
  End

  Engine Band 

    UseSymmetry False

    NumericalQuality good

    Tails bas=1e-10

    KSpace
      Regular
        NumberOfPoints 5 5
      End
    End

    Basis
      Type DZP
      Core Large
    End

    Convergence
     Criterion 1E-8
    End

    Restart
      File MoS2.results/band.rkf
      SCF
    End

    NewResponse
      nFreq        3
      FreqLow      2.0
      FreqHigh     2.7
      ActiveESpace 10.0
      ActiveXYZ    T T F
    End

    NewResponseSCF
      nCycle       50
      Criterion    1E-3
      DIIS  MinSamples=3 MixingFactor=0.5 MaximumCoefficient=20
    End

    NewResponseKSPACE
      subsimp 10
      eta     1e-6
    End
  EndEngine

eor

# ============
# Extract info 
# ============

$AMSBIN/amsreport MoS2_restart.results/band.rkf RESPDIELRE
$AMSBIN/amsreport MoS2_restart.results/band.rkf RESPDIELIM

# The results are accessible via the standard output or via the prop.kf file.
# For the latter, one can use the AMSreport command $AMSBIN/amsreport prop.kf
# RESPDIELRE and $AMSBIN/amsreport prop.kf RESPDIELIM to print the components
# of the dielectric function for the real (RESPDIELRE) and imaginary
# (RESPDIELIM) part separately. In the following tables, only the diagonal
# components are presented:

# Real part
# Frequency (au)  epsilon_1(XX)  epsilon_1(YY)  epsilon_1(ZZ)
# 0.0735          8.1622063      8.1788067      1.8845925
# 0.0772          8.7718566      8.7960299      1.8891231
# 0.0808          9.6251443      9.6631930      1.8941277
# 0.0845         10.9457271     11.0126367      1.8996502
# 0.0882         13.4618956     13.6001321      1.9057858
# 0.0919         26.5135344     25.9300685      1.9126665
# 0.0955          6.1134118      4.1756368      1.9204849
# 0.0992          6.2789015      4.6880515      1.9295347
# 0.1029         13.7665058     11.5484340      1.9403044
# 0.1066         -7.2575153     -5.8285172      1.9537079
# 0.1102         -0.7937277      1.2661253      1.9718981

# Imaginary part
# Frequency (au)  epsilon_2(XX) epsilon_2(YY)  epsilon_2(ZZ)
# 0.0735          0.0015601     0.0015758      0.0000213
# 0.0772          0.0020566     0.0020839      0.0000200
# 0.0808          0.0029274     0.0029798      0.0000216
# 0.0845          0.0047632     0.0048794      0.0000231
# 0.0882          0.0104743     0.0107877      0.0000246
# 0.0919          0.2658531     0.1942899      0.0000264
# 0.0955         12.8856772    14.5286319      0.0000294
# 0.0992         9.7571573     10.1567455      0.0000338
# 0.1029          7.5936072     6.7674596      0.0000399
# 0.1066          13.0264038    9.5897946      0.0000487
# 0.1102          0.2483041     0.3222301      0.0000676

# The more convenient option is to plot the spectral data directly with the help
# of AMSspectra. Just type: $AMSBIN/amsspectra prop.kf