PMASS - Revision history

Tbucko at 19:47, 15 February 2026

2026-02-15T19:47:24Z

← Older revision		Revision as of 19:47, 15 February 2026
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	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|S. Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of ~~a harmonic lattice of with~~ a cubic cell can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.		As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|S. Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the harmonic frequency of oscillation of a cubic cell can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.

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Tbucko at 19:46, 15 February 2026

2026-02-15T19:46:18Z

← Older revision		Revision as of 19:46, 15 February 2026
Line 10:		Line 10:
	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|S. Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of lattice of a cubic ~~harmonic system~~ can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.		As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|S. Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of a harmonic lattice of with a cubic cell can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.

	== Related tags and articles ==		== Related tags and articles ==

Tbucko: small correction in newly added citation

2026-02-15T19:44:31Z

small correction in newly added citation

← Older revision		Revision as of 19:44, 15 February 2026
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	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|~~Shuichi~~ Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of lattice of a cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.		As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|S. Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of lattice of a cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.

	== Related tags and articles ==		== Related tags and articles ==

Tbucko: added citation to Klein's work

2026-02-15T19:43:37Z

added citation to Klein's work

← Older revision		Revision as of 19:43, 15 February 2026
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	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein, the frequency of oscillation of lattice of a cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.		As demonstrated by Nosé and Klein<ref>[[doi:10.1080/00268978300102851\|Shuichi Nosé and M. L. Klein, Mol. Phys. 50, 1055 (1983)]]</ref>, the frequency of oscillation of lattice of a cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.

	== Related tags and articles ==		== Related tags and articles ==

Tbucko at 19:36, 15 February 2026

2026-02-15T19:36:01Z

← Older revision		Revision as of 19:36, 15 February 2026
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	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should be doubled ~~as well~~		As demonstrated by Nosé and Klein, the frequency of oscillation of lattice of a cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should also be doubled.

	== Related tags and articles ==		== Related tags and articles ==

Tbucko at 19:33, 15 February 2026

2026-02-15T19:33:51Z

← Older revision		Revision as of 19:33, 15 February 2026
Line 10:		Line 10:
	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system ~~is proportional to~~ <math>\sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively.		As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system can be expressed as <math>\omega_L = \sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively. Should <math>\omega_L</math> remain the same upon (say) doubling one of the cell dimensions, the {{TAG\|PMASS}} should be doubled as well

	== Related tags and articles ==		== Related tags and articles ==

Tbucko at 19:30, 15 February 2026

2026-02-15T19:30:31Z

← Older revision		Revision as of 19:30, 15 February 2026
Line 10:		Line 10:
	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system is proportional to <math>\sqrt{\frac{3BL}{W}}</math>		As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system is proportional to <math>\sqrt{\frac{3BL}{W}}</math>, where <math>B</math>, <math>L</math>, and <math>W</math> are bulk modulus, size of the unit cell, and mass of the lattice degrees-of-freedom, respectively.

	== Related tags and articles ==		== Related tags and articles ==

Tbucko at 19:27, 15 February 2026

2026-02-15T19:27:16Z

← Older revision		Revision as of 19:27, 15 February 2026
Line 9:		Line 9:

	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

			As demonstrated by Nosé and Klein, frequency of oscillation of lattice of cubic harmonic system is proportional to <math>\sqrt{\frac{3BL}{W}}</math>

	== Related tags and articles ==		== Related tags and articles ==

Singraber at 22:43, 9 November 2023

2023-11-09T22:43:33Z

← Older revision		Revision as of 22:43, 9 November 2023
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	Description: {{TAG\|PMASS}} assigns a fictitious mass (in amu) to the lattice degrees-of-freedom in case of Parrinello-Rahman dynamics (in case VASP was compiled with [[Precompiler options#-Dtbdyn\|-Dtbdyn]]).		Description: {{TAG\|PMASS}} assigns a fictitious mass (in amu) to the lattice degrees-of-freedom in case of Parrinello-Rahman dynamics (in case VASP was compiled with [[Precompiler options#-Dtbdyn\|-Dtbdyn]]).
	----		----
	When running ''NpT'' simulations with a [[MDALGO#LangevinEOM\|Langevin thermostat]]<ref name="Allen91"/> ({{TAG\|MDALGO}}=3), using the method of [[~~MDALGO#ParrinelloRahman~~\|Parrinello and Rahman]],<ref name="Parrinello80"/><ref name="Parrinello81"/> a fictitious mass (in amu) for the lattice degrees-of-freedom has to be assigned using the {{TAG\|PMASS}} tag.		When running ''NpT'' simulations with a [[MDALGO#LangevinEOM\|Langevin thermostat]]<ref name="Allen91"/> ({{TAG\|MDALGO}}=3), using the method of [[NpT_ensemble\|Parrinello and Rahman]],<ref name="Parrinello80"/><ref name="Parrinello81"/> a fictitious mass (in amu) for the lattice degrees-of-freedom has to be assigned using the {{TAG\|PMASS}} tag.
	The friction coefficient for lattice degrees-of-freedom have to be specified (in ps<sup>-1</sup>) by means of the {{TAG\|LANGEVIN_GAMMA_L}} tag.		The friction coefficient for lattice degrees-of-freedom have to be specified (in ps<sup>-1</sup>) by means of the {{TAG\|LANGEVIN_GAMMA_L}} tag.

Kresse at 13:52, 11 April 2023

2023-04-11T13:52:18Z

← Older revision		Revision as of 13:52, 11 April 2023
Line 8:		Line 8:
	The friction coefficients γ for the atomic degrees-of-freedom are specified using the {{TAG\|LANGEVIN_GAMMA}} tag.		The friction coefficients γ for the atomic degrees-of-freedom are specified using the {{TAG\|LANGEVIN_GAMMA}} tag.

	The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in a MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.		The optimal setting for {{TAG\|PMASS}} depends very much on the particular system at hand and can be considered as a compromise between two opposing factors: too large values lead to very slow variation of lattice degrees of freedom (and hence the sampling becomes inefficient) while too small value can lead to too large geometric changes in an MD step and hence may cause numerical problems. We strongly recommend to make careful tests with various settings before performing the production run.

	== Related tags and articles ==		== Related tags and articles ==