mirror of https://github.com/abinit/abinit.git
127 lines
3.6 KiB
Scilab
127 lines
3.6 KiB
Scilab
// Scilab script to compute the Faust-Henry coefficient in
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// zinc-blende semiconductors
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// See Eqs. (2.90) - (2.94) of Light Scattering in Solids II.
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clear
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// ----------------------------------------------------------------------------
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// ------- Parameters taken from the output files of ABINIT and ANADDB --------
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// ----------------------------------------------------------------------------
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// Name of the semiconductor
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sc = 'AlAs'
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// Unit cell volume in bohr^3
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ucvol = 3.0109659E+02
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// Atomic masses
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m1 = 0.26981539000000D+02
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m2 = 0.74921590000000D+02
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// Born effective charge
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zeff = 2.105999E+00
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// Electronic dielectric constant
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epsel = 9.94846084
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// Non-linear optical susceptibilities (d_123 in pm/V)
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d0mks = 32.772254
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// First-order change in the electronic dielectric susceptibility
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// induced by a displacement of atom 1 (Bohr^-1)
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dchidtau = -0.099889084
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// Energy (hartree) of TO and LO modes
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wto = 1.641481E-03
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wlo = 1.791368E-03
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// ----------------------------------------------------------------------------
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// -------------------------- Fundamental constants ---------------------------
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// ----------------------------------------------------------------------------
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e_Cb = 1.602176462e-19;
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amu_emass = 1.66053873e-27/9.10938188e-31;
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eps0 =8.854187817e-12;
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Ha_cmm1 = 219474.6313710;
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Bohr_Ang = 0.5291772083;
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// Factor to convert the nlo susceptibilities from a.u. to pm/V
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fac = 4*%pi*(Bohr_Ang**2)*1.0e-8*4*%pi*eps0/e_Cb
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// Unit for output
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unix('if [ -f fausthenry.out ]; then rm -f fausthenry.out; fi')
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unit = file('open','fausthenry.out');
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// ----------------------------------------------------------------------------
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// ----- Computation of the Faust-Henry coefficient and related quantities ----
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// ----------------------------------------------------------------------------
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mes = ' Raman scattering in ' + sc
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write(unit,mes)
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mes = ' ========================'
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write(unit,mes)
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write(unit,'')
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mes = ' General parameters:'
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write(unit,mes)
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mes = ' epsel = ' + string(epsel)
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write(unit,mes)
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mes = ' d_123 (pm/V) = ' + string(d0mks)
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write(unit,mes)
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mes = ' zeff = ' + string(zeff)
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write(unit,mes)
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mes = ' wto (cm^-1) = ' + string(wto*Ha_cmm1)
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write(unit,mes)
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mes = ' wlo (cm^-1) = ' + string(wlo*Ha_cmm1)
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write(unit,mes)
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write(unit,'')
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d0au = d0mks/fac;
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mu = amu_emass*m1*m2/(m1 + m2);
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cfausth = zeff*dchidtau/(4*d0au*mu*wto**2);
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mes = ' Faust-Henry coefficient:'
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write(unit,mes)
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mes = ' C = ' + string(cfausth)
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write(unit,mes)
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write(unit,'')
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ato = ucvol*dchidtau*Bohr_Ang**2;
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alo = ato*(1-(wlo**2 - wto**2)/(cfausth*wto**2))
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mes = ' Raman polarizability (A^2):'
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write(unit,mes)
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mes = ' ato = ' + string(ato)
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write(unit,mes)
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mes = ' alo = ' + string(alo)
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write(unit,mes)
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write(unit,'')
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dto = dchidtau;
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dlo = dchidtau*(1-(wlo**2 - wto**2)/(cfausth*wto**2));
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mes = ' Raman tensor of TO and LO modes:'
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write(unit,mes)
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mes = ' dto = ' + string(dto)
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write(unit,mes)
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mes = ' dlo = ' + string(dlo)
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write(unit,mes)
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mes = ' dlo/dto = ' + string(dlo/dto)
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write(unit,mes)
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write(unit,'')
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enhanc = (wto/wlo)*(dlo/dto)**2
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mes = ' Enhancement factor:'
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write(unit,mes)
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mes = ' (wto/wlo)*(dlo/dto)**2 = ' + string(enhanc)
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write(unit,mes)
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write(unit,'')
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rijk = -4*d0mks*(1+cfausth)/epsel**2,
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mes = ' Electrooptic tensor (pm/V):'
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write(unit,mes)
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mes = ' rijk = ' + string(rijk)
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write(unit,mes)
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// ----------------------------------------------------------------------------
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file('close',unit)
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quit
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