Dielectric properties of SiC - Revision history

Karsai: /* Download */

2019-11-14T13:21:13Z

Download

← Older revision		Revision as of 13:21, 14 November 2019
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	{{Template:optics_dielectric}}		{{Template:optics_dielectric}}

	~~Back to the [[The_VASP_Manual\|main page]].~~

	[[Category:Examples]]		[[Category:Examples]]

Karsai: /* Download */

2019-11-14T09:49:32Z

Download

← Older revision		Revision as of 09:49, 14 November 2019
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	== Download ==		== Download ==
	[~~http~~:~~//www.vasp.at/vasp-workshop/examples/~~SiC_dielectric.tgz SiC_dielectric.tgz]		[[Media:SiC_dielectric.tgz\| SiC_dielectric.tgz]]

	{{Template:optics_dielectric}}		{{Template:optics_dielectric}}

Karsai at 11:09, 4 October 2019

2019-10-04T11:09:03Z

← Older revision		Revision as of 11:09, 4 October 2019
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	[[File:Fig dielectric properties SiC 2.png\|600px]]		[[File:Fig dielectric properties SiC 2.png\|600px]]

	~~== Download ==~~
	~~[http://www.vasp.at/vasp-workshop/examples/SiC_dielectric.tgz SiC_dielectric.tgz]~~

	== References ==		== References ==
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	<ref name="souza:prl:02">[http://link.aps.org/doi/10.1103/PhysRevLett.89.117602 I. Souza, J. Íñiguez, and D. Vanderbilt, Phys. Rev. Lett. 89, 117602 (2002).]</ref>		<ref name="souza:prl:02">[http://link.aps.org/doi/10.1103/PhysRevLett.89.117602 I. Souza, J. Íñiguez, and D. Vanderbilt, Phys. Rev. Lett. 89, 117602 (2002).]</ref>
	</references>		</references>

			== Download ==
			[http://www.vasp.at/vasp-workshop/examples/SiC_dielectric.tgz SiC_dielectric.tgz]

	{{Template:optics_dielectric}}		{{Template:optics_dielectric}}

Karsai at 13:33, 7 June 2019

2019-06-07T13:33:03Z

← Older revision		Revision as of 13:33, 7 June 2019
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	{{Template:optics_dielectric}}		{{Template:optics_dielectric - Tutorial}}

	== Task ==		== Task ==

Karsai at 18:06, 10 November 2017

2017-11-10T18:06:52Z

← Older revision		Revision as of 18:06, 10 November 2017
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	{{TAGBL\|EDIFF}} = 1.E-8		{{TAGBL\|EDIFF}} = 1.E-8

	*{{TAG\|KPOINTS}} (see~~{{Template:optics_dielectric}}~~ KPOINTS.6)		*{{TAG\|KPOINTS}} (see KPOINTS.6)
	<pre>		<pre>
	6x6x6		6x6x6
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	To compute the frequency dependent dielectric function in the independent-particle (IP) picture		To compute the frequency dependent dielectric function in the independent-particle (IP) picture
	we restart from the {{FILE\|WAVECAR}} of the previous run, with the following {{FILE\|INCAR}}		we restart from the {{FILE\|WAVECAR}} of the previous run, with the following {{FILE\|INCAR}}
	~~{{Template:optics_dielectric}}~~
	*{{TAG\|INCAR}} (see INCAR.LOPTICS)		*{{TAG\|INCAR}} (see INCAR.LOPTICS)

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	cat >plotfile<<!		cat >plotfile<<!
	# set term postscript enhanced eps colour lw 2 "Helvetica" 20		# set term postscript enhanced eps colour lw 2 "Helvetica" 20
	# set output "optics.~~{{Template:optics_dielectric}}~~eps"		# set output "optics.eps"
	plot [0:25] "imag.dat" using (\$1):(\$2) w lp, "real.dat" using (\$1):(\$2) w lp		plot [0:25] "imag.dat" using (\$1):(\$2) w lp, "real.dat" using (\$1):(\$2) w lp
	!		!
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	in the {{FILE\|INCAR}} file.		in the {{FILE\|INCAR}} file.
	The derivative of the~~{{Template:optics_dielectric}}~~ cell-periodic part of the wave function w.r.t. the Bloch vector is then computed		The derivative of the cell-periodic part of the wave function w.r.t. the Bloch vector is then computed
	by means of a fourth-order finite difference stencil, in the spirit of Eqs. 96 and 97 of <ref name="nunes:prb:01"/>.		by means of a fourth-order finite difference stencil, in the spirit of Eqs. 96 and 97 of <ref name="nunes:prb:01"/>.

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	# Frequency dependent dielectric tensor with and		# Frequency dependent dielectric tensor with and
	# without local ~~fiel{{Template:optics_dielectric}}d~~ effects in RPA		# without local field effects in RPA
	# N.B.: beware one first has to have done a		# N.B.: beware one first has to have done a
	# calculation with {{TAGBL\|ALGO}}=Exact, {{TAGBL\|LOPTICS}}=.TRUE.		# calculation with {{TAGBL\|ALGO}}=Exact, {{TAGBL\|LOPTICS}}=.TRUE.
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	{{TAGBL\|LWAVE }}= .FALSE.		{{TAGBL\|LWAVE }}= .FALSE.
	{{TAGBL\|LCHARG}}= .~~F{{Template:optics_dielectric}}ALSE~~.		{{TAGBL\|LCHARG}}= .FALSE.


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	in the {{FILE\|OUTCAR}} file.		in the {{FILE\|OUTCAR}} file.
	~~{{Template:optics_dielectric}}~~
	To include local field effects beyond the RPA, i.e., contributions from DFT exchange and correlation, one has to specify		To include local field effects beyond the RPA, i.e., contributions from DFT exchange and correlation, one has to specify

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	in the {{FILE\|OUTCAR}} file.		in the {{FILE\|OUTCAR}} file.
	~~{{Template:optics_dielectric}}~~
	The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both		The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both
	in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot'':		in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot'':
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	{if ($4=="dielectric") {a[i]=$1 ; b[i]=$2 ; c[i]=$3 ; i=i+1}} \		{if ($4=="dielectric") {a[i]=$1 ; b[i]=$2 ; c[i]=$3 ; i=i+1}} \
	END{for (j=1;j<i;j++) print a[j],b[j],c[j]}' OUTCAR > chi.dat		END{for (j=1;j<i;j++) print a[j],b[j],c[j]}' OUTCAR > chi.dat
	~~{{Template:optics_dielectric}}~~
	cat >plotfile<<!		cat >plotfile<<!
	# set term postscript enhanced eps colour lw 2 "Helvetica" 20		# set term postscript enhanced eps colour lw 2 "Helvetica" 20
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	</pre>		</pre>

	If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=''.TRUE.'' run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions ~~{{Template:optics_dielectric}}~~computed with {{TAG\|LOPTICS}}=''.TRUE.'' and {{TAG\|ALGO}}=''CHI''.		If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=''.TRUE.'' run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions computed with {{TAG\|LOPTICS}}=''.TRUE.'' and {{TAG\|ALGO}}=''CHI''.

	<pre>		<pre>

Karsai at 11:14, 10 August 2017

2017-08-10T11:14:02Z

← Older revision		Revision as of 11:14, 10 August 2017
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	{{TAGBL\|EDIFF}} = 1.E-8		{{TAGBL\|EDIFF}} = 1.E-8

	*{{TAG\|KPOINTS}} (see KPOINTS.6)		*{{TAG\|KPOINTS}} (see{{Template:optics_dielectric}} KPOINTS.6)
	<pre>		<pre>
	6x6x6		6x6x6
Line 195:		Line 195:
	To compute the frequency dependent dielectric function in the independent-particle (IP) picture		To compute the frequency dependent dielectric function in the independent-particle (IP) picture
	we restart from the {{FILE\|WAVECAR}} of the previous run, with the following {{FILE\|INCAR}}		we restart from the {{FILE\|WAVECAR}} of the previous run, with the following {{FILE\|INCAR}}
			{{Template:optics_dielectric}}
	*{{TAG\|INCAR}} (see INCAR.LOPTICS)		*{{TAG\|INCAR}} (see INCAR.LOPTICS)

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	cat >plotfile<<!		cat >plotfile<<!
	# set term postscript enhanced eps colour lw 2 "Helvetica" 20		# set term postscript enhanced eps colour lw 2 "Helvetica" 20
	# set output "optics.eps"		# set output "optics.{{Template:optics_dielectric}}eps"
	plot [0:25] "imag.dat" using (\$1):(\$2) w lp, "real.dat" using (\$1):(\$2) w lp		plot [0:25] "imag.dat" using (\$1):(\$2) w lp, "real.dat" using (\$1):(\$2) w lp
	!		!
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	in the {{FILE\|INCAR}} file.		in the {{FILE\|INCAR}} file.
	The derivative of the cell-periodic part of the wave function w.r.t. the Bloch vector is then computed		The derivative of the{{Template:optics_dielectric}} cell-periodic part of the wave function w.r.t. the Bloch vector is then computed
	by means of a fourth-order finite difference stencil, in the spirit of Eqs. 96 and 97 of <ref name="nunes:prb:01"/>.		by means of a fourth-order finite difference stencil, in the spirit of Eqs. 96 and 97 of <ref name="nunes:prb:01"/>.

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	# Frequency dependent dielectric tensor with and		# Frequency dependent dielectric tensor with and
	# without local ~~field~~ effects in RPA		# without local fiel{{Template:optics_dielectric}}d effects in RPA
	# N.B.: beware one first has to have done a		# N.B.: beware one first has to have done a
	# calculation with {{TAGBL\|ALGO}}=Exact, {{TAGBL\|LOPTICS}}=.TRUE.		# calculation with {{TAGBL\|ALGO}}=Exact, {{TAGBL\|LOPTICS}}=.TRUE.
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	{{TAGBL\|LWAVE }}= .FALSE.		{{TAGBL\|LWAVE }}= .FALSE.
	{{TAGBL\|LCHARG}}= .~~FALSE~~.		{{TAGBL\|LCHARG}}= .F{{Template:optics_dielectric}}ALSE.


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	in the {{FILE\|OUTCAR}} file.		in the {{FILE\|OUTCAR}} file.
			{{Template:optics_dielectric}}
	To include local field effects beyond the RPA, i.e., contributions from DFT exchange and correlation, one has to specify		To include local field effects beyond the RPA, i.e., contributions from DFT exchange and correlation, one has to specify

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	in the {{FILE\|OUTCAR}} file.		in the {{FILE\|OUTCAR}} file.
			{{Template:optics_dielectric}}
	The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both		The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both
	in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot'':		in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot'':
Line 324:		Line 324:
	{if ($4=="dielectric") {a[i]=$1 ; b[i]=$2 ; c[i]=$3 ; i=i+1}} \		{if ($4=="dielectric") {a[i]=$1 ; b[i]=$2 ; c[i]=$3 ; i=i+1}} \
	END{for (j=1;j<i;j++) print a[j],b[j],c[j]}' OUTCAR > chi.dat		END{for (j=1;j<i;j++) print a[j],b[j],c[j]}' OUTCAR > chi.dat
			{{Template:optics_dielectric}}
	cat >plotfile<<!		cat >plotfile<<!
	# set term postscript enhanced eps colour lw 2 "Helvetica" 20		# set term postscript enhanced eps colour lw 2 "Helvetica" 20
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	</pre>		</pre>

	If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=''.TRUE.'' run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions computed with {{TAG\|LOPTICS}}=''.TRUE.'' and {{TAG\|ALGO}}=''CHI''.		If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=''.TRUE.'' run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions {{Template:optics_dielectric}}computed with {{TAG\|LOPTICS}}=''.TRUE.'' and {{TAG\|ALGO}}=''CHI''.

	<pre>		<pre>
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	<ref name="souza:prl:02">[http://link.aps.org/doi/10.1103/PhysRevLett.89.117602 I. Souza, J. Íñiguez, and D. Vanderbilt, Phys. Rev. Lett. 89, 117602 (2002).]</ref>		<ref name="souza:prl:02">[http://link.aps.org/doi/10.1103/PhysRevLett.89.117602 I. Souza, J. Íñiguez, and D. Vanderbilt, Phys. Rev. Lett. 89, 117602 (2002).]</ref>
	</references>		</references>
	~~----~~
	~~[[VASP tutorials\|To the list of examples]] or~~ to the [[The_VASP_Manual\|main page]]		{{Template:optics_dielectric}}

			Back to the [[The_VASP_Manual\|main page]].

	[[Category:Examples]]		[[Category:Examples]]

Karsai: /* References */

2017-07-04T11:13:14Z

References

← Older revision		Revision as of 11:13, 4 July 2017
Line 406:		Line 406:
	</references>		</references>
	----		----
	[[~~VASP_example_calculations~~\|To the list of examples]] or to the [[The_VASP_Manual\|main page]]		[[VASP tutorials\|To the list of examples]] or to the [[The_VASP_Manual\|main page]]

	[[Category:Examples]]		[[Category:Examples]]

Karsai: /* Including local field effects */

2017-05-26T12:39:41Z

Including local field effects

← Older revision		Revision as of 12:39, 26 May 2017
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	</pre>		</pre>

	If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=.TRUE. run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions computed with {{TAG\|LOPTICS}}=.TRUE. and {{TAG\|ALGO}}=CHI.		If you have kept a copy of the {{FILE\|vasprun.xml}} of the {{TAG\|LOPTICS}}=''.TRUE.'' run (e.g., <tt>vasprun_loptics.xml</tt>), you might execute <tt>plotall</tt> to compare the dielectric functions computed with {{TAG\|LOPTICS}}=''.TRUE.'' and {{TAG\|ALGO}}=''CHI''.

	<pre>		<pre>
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	</pre>		</pre>

	Why are the dielectric functions in independent-particle picture from the {{TAG\|LOPTICS}}=.TRUE. and the {{TAG\|ALGO}}=CHI calculations different?		Why are the dielectric functions in independent-particle picture from the {{TAG\|LOPTICS}}=''.TRUE.'' and the {{TAG\|ALGO}}=''CHI'' calculations different?

	Hints:		Hints:
	*What {{TAG\|CSHIFT}} is used in the {{TAG\|ALGO}}=CHI calculation?		*What {{TAG\|CSHIFT}} is used in the {{TAG\|ALGO}}=''CHI'' calculation?

	Try redoing the {{TAG\|LOPTICS}}=.TRUE. calculation with the same {{TAG\|CSHIFT}} as VASP chose for the {{TAG\|ALGO}}=CHI calculation (see INCAR.LOPTICS2):		Try redoing the {{TAG\|LOPTICS}}=''.TRUE.'' calculation with the same {{TAG\|CSHIFT}} as VASP chose for the {{TAG\|ALGO}}=''CHI'' calculation (see INCAR.LOPTICS2):

	CSHIFT=0.466		CSHIFT=0.466

	*~~And redo~~ {{TAG\|ALGO}}=CHI calculation with {{TAG\|LSPECTRAL}}=.FALSE. in the {{TAG\|ALGO}}=CHI calculation (see INCAR.CHI2).		*Redo the {{TAG\|ALGO}}=''CHI'' calculation with {{TAG\|LSPECTRAL}}=''.FALSE.'' in the {{TAG\|ALGO}}=''CHI'' calculation (see INCAR.CHI2).

	and compare the dielectric functions again.		and compare the dielectric functions again.

Karsai: /* Including local field effects */

2017-05-26T12:37:36Z

Including local field effects

← Older revision		Revision as of 12:37, 26 May 2017
Line 312:		Line 312:

	The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both		The following bash-script (<tt>plotchi</tt>) uses ''awk'' to extract the frequency dependent dielectric constant, both
	in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot''.		in the independent-particle picture as well as including local field effects (either in DFT or in the RPA) and plots the real and imaginary components using ''gnuplot'':

	<pre>		<pre>

Karsai: /* Including local field effects */

2017-05-26T12:33:17Z

Including local field effects

← Older revision		Revision as of 12:33, 26 May 2017
Line 291:		Line 291:
	in the {{FILE\|OUTCAR}} file.		in the {{FILE\|OUTCAR}} file.

	Per default, for {{TAG\|ALGO}}=CHI, local field effects are included at the level of the RPA ({{TAG\|LRPA}}=.TRUE.), i.e., limited to Hartree contributions only.		Per default, for {{TAG\|ALGO}}=''CHI'', local field effects are included at the level of the RPA ({{TAG\|LRPA}}=''.TRUE.''), i.e., limited to Hartree contributions only.

	See the information after		See the information after