Cd Si volume relaxation - Revision history

Karsai: /* Download */

2019-11-14T08:32:27Z

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	== Download ==		== Download ==
	[~~http~~:~~//www.vasp.at/vasp-workshop/examples/diamondSivolrel~~.tgz diamondSivolrel.tgz]		[[Media:DiamondSivolrel.tgz\| diamondSivolrel.tgz]]

	{{Template:Bulk_systems}}		{{Template:Bulk_systems}}

Vaspmaster: /* Calculation */

2019-06-23T20:25:24Z

Calculation

← Older revision		Revision as of 20:25, 23 June 2019
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	*From equation of states we determine lattice parameter of <math>a=5.4687</math> Å (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).		*From equation of states we determine lattice parameter of <math>a=5.4687</math> Å (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).

	*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> ~~<math>\AA</math>~~.		*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> Å.

	*Difference can be due to pulay stress (especially when the relaxation starts far away from equilibrium):		*Difference can be due to pulay stress (especially when the relaxation starts far away from equilibrium):

Vaspmaster: /* Calculation */

2019-06-23T20:25:00Z

Calculation

← Older revision		Revision as of 20:25, 23 June 2019
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	**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)		**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)

	*From equation of states we determine lattice parameter of <math>a=5.4687</math> ~~<math>\AA</math>~~ (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).		*From equation of states we determine lattice parameter of <math>a=5.4687</math> Å (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).

	*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> <math>\AA</math>.		*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> <math>\AA</math>.

Vaspmaster: /* Calculation */

2019-06-23T20:24:15Z

Calculation

← Older revision		Revision as of 20:24, 23 June 2019
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	*To determine the equilibrium volume we can:		*To determine the equilibrium volume we can:
	**Fit the energz over a certain volume range to an equation of state (see {{TAG\|cd_Si}}.		**Fit the energz over a certain volume range to an equation of state (see {{TAG\|cd_Si}}).
	**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)		**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)

Karsai at 13:20, 7 June 2019

2019-06-07T13:20:44Z

← Older revision		Revision as of 13:20, 7 June 2019
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	{{Template:Bulk_systems}}		{{Template:Bulk_systems - Tutorial}}

	== Task ==		== Task ==

Karsai: /* Download */

2017-08-10T11:03:58Z

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← Older revision		Revision as of 11:03, 10 August 2017
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	== Download ==		== Download ==
	[http://www.vasp.at/vasp-workshop/examples/diamondSivolrel.tgz diamondSivolrel.tgz]		[http://www.vasp.at/vasp-workshop/examples/diamondSivolrel.tgz diamondSivolrel.tgz]
	~~----~~
	~~[[VASP tutorials\|To the list of examples]] or~~ to the [[The_VASP_Manual\|main page]]		{{Template:Bulk_systems}}

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

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

Karsai: /* Download */

2017-07-04T11:06:51Z

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← Older revision		Revision as of 11:06, 4 July 2017
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	[http://www.vasp.at/vasp-workshop/examples/diamondSivolrel.tgz diamondSivolrel.tgz]		[http://www.vasp.at/vasp-workshop/examples/diamondSivolrel.tgz diamondSivolrel.tgz]
	----		----
	[[~~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 at 19:12, 8 May 2017

2017-05-08T19:12:29Z

← Older revision		Revision as of 19:12, 8 May 2017
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	*To remedy this increase the plane wave cutoff by at least 30% (here we used {{TAG\|ENMAX}}=400 instead of 240) and use a small {{TAG\|EDIFF}}.		*To remedy this increase the plane wave cutoff by at least 30% (here we used {{TAG\|ENMAX}}=400 instead of 240) and use a small {{TAG\|EDIFF}}.

			=== Summary ===

			*Calculation of the equilibrium volume:
			**FIt the energy over a certain volume range to an equation of state.
			**When internal degrees of freedom exist (e.g. c/a), the structure must be optimized. Use a conjugate-gradient algorithm ({{TAG\|IBRION}}=2) and at each volume do e.g. 10 ionic steps ({{TAG\|NSW}}=10) and allow change of internal parameters and shape ({{TAG\|ISIF}}=4).

			*Simpler but less reliable: relaxing all degrees of freedom including volume.
			**To relax all degrees of freedom use {{TAG\|ISIF}}=3 (internal coordinates, shape and volume).
			**Mind pulay stress problem. Increase plane wave cutoff by 25-30% when the volume is allowed to change.

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Karsai at 19:05, 8 May 2017

2017-05-08T19:05:01Z

← Older revision		Revision as of 19:05, 8 May 2017
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	2.734185321 0.000000000 2.734185321 0.182869828 -0.182869828 0.182869828		2.734185321 0.000000000 2.734185321 0.182869828 -0.182869828 0.182869828
	2.734185321 2.734185321 0.000000000 0.182869828 0.182869828 -0.182869828		2.734185321 2.734185321 0.000000000 0.182869828 0.182869828 -0.182869828


			*To remedy this increase the plane wave cutoff by at least 30% (here we used {{TAG\|ENMAX}}=400 instead of 240) and use a small {{TAG\|EDIFF}}.

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Karsai at 19:03, 8 May 2017

2017-05-08T19:03:08Z

← Older revision		Revision as of 20:25, 23 June 2019
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	**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)		**Alternatively we relax the structure with VASP "on the fly" ({{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3)

	*From equation of states we determine lattice parameter of <math>a=5.4687</math> ~~<math>\AA</math>~~ (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).		*From equation of states we determine lattice parameter of <math>a=5.4687</math> Å (volume scan plus Murnaghan EOS using {{TAG\|ENMAX}}=400).

	*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> <math>\AA</math>.		*From relaxations using {{TAG\|IBRION}}=2 and {{TAG\|ISIF}}=3 we get <math>a=5.4684</math> <math>\AA</math>.

← Older revision		Revision as of 19:03, 8 May 2017
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	*Difference can be due to pulay stress (especially when the relaxation starts far away from equilibrium):		*Difference can be due to pulay stress (especially when the relaxation starts far away from equilibrium):
	-------------------------------------------------------------------------------------		-------------------------------------------------------------------------------------
	Total 0.00155 0.00155 0.00155 -0.00000 -0.00000 0.00000		Total 0.00155 0.00155 0.00155 -0.00000 -0.00000 0.00000
	in kB 0.06056 0.06056 0.06056 -0.00000 -0.00000 0.00000		in kB 0.06056 0.06056 0.06056 -0.00000 -0.00000 0.00000
	external pressure = 0.06 kB Pullay stress = 0.00 kB		external pressure = 0.06 kB Pullay stress = 0.00 kB


	VOLUME and BASIS-vectors are now :		VOLUME and BASIS-vectors are now :
	-----------------------------------------------------------------------------		-----------------------------------------------------------------------------
	energy-cutoff : 400.00		energy-cutoff : 400.00
	volume of cell : 40.88		volume of cell : 40.88
	direct lattice vectors reciprocal lattice vectors		direct lattice vectors reciprocal lattice vectors
	0.000000000 2.734185321 2.734185321 -0.182869828 0.182869828 0.182869828		0.000000000 2.734185321 2.734185321 -0.182869828 0.182869828 0.182869828
	2.734185321 0.000000000 2.734185321 0.182869828 -0.182869828 0.182869828		2.734185321 0.000000000 2.734185321 0.182869828 -0.182869828 0.182869828
	2.734185321 2.734185321 0.000000000 0.182869828 0.182869828 -0.182869828		2.734185321 2.734185321 0.000000000 0.182869828 0.182869828 -0.182869828

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