Simple charge-transfer model to explain the electrical response of hydrogen chains

Adrienn Ruzsinszky, John P. Perdew, G. Csonka

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Linear H2n chains of H2 units are experimentally unrealizable but simple and widely studied exemplars of the response coefficients (polarizabilities and hyperpolarizabilities) of polymer chains in uniform longitudinal electric fields. They show two surprising features: (1) Their response coefficients, unlike those of bulk solids, show a strong nonlinear dependence upon length or n. (2) Their response coefficients are seriously too large when computed with standard local or semilocal density functionals, but are much more correct when computed with self-interaction-free approaches (including Hartree-Fock). We propose a simple charge-transfer model which explains both of these effects in analytic terms. In this model, charge is transferred between H2 units paired up at equal distances from but on opposite sides of the chain center. All symmetric pairs of H2 units, not just the one for the chain ends, are included. This transfer is driven by the external electric field, and opposed by the chemical hardness of each H2 unit. Unlike the situation in a bulk solid, this charge transfer is not suppressed (or even much affected) by electrostatic interactions among the transferred charges for n≤7. Self-interaction-free approaches increase the chemical hardness of an H2 unit in comparison with semilocal density functionals, and so reduce the charge transfer. The physical picture behind the model is validated and its limitations are revealed by an analysis of the charge density from self-consistent electronic structure calculations. An appendix presents an accurate method to extract the hyperpolarizability from self-consistent calculations, and its results.

Original languageEnglish
Article number022513
JournalPhysical Review A
Volume78
Issue number2
DOIs
Publication statusPublished - Aug 15 2008

Fingerprint

charge transfer
functionals
hydrogen
coefficients
hardness
electric fields
interactions
electrostatics
electronic structure
polymers

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physics and Astronomy(all)

Cite this

Simple charge-transfer model to explain the electrical response of hydrogen chains. / Ruzsinszky, Adrienn; Perdew, John P.; Csonka, G.

In: Physical Review A, Vol. 78, No. 2, 022513, 15.08.2008.

Research output: Contribution to journalArticle

@article{4a97a23b43c1466c9fc6cb6eae80ed67,
title = "Simple charge-transfer model to explain the electrical response of hydrogen chains",
abstract = "Linear H2n chains of H2 units are experimentally unrealizable but simple and widely studied exemplars of the response coefficients (polarizabilities and hyperpolarizabilities) of polymer chains in uniform longitudinal electric fields. They show two surprising features: (1) Their response coefficients, unlike those of bulk solids, show a strong nonlinear dependence upon length or n. (2) Their response coefficients are seriously too large when computed with standard local or semilocal density functionals, but are much more correct when computed with self-interaction-free approaches (including Hartree-Fock). We propose a simple charge-transfer model which explains both of these effects in analytic terms. In this model, charge is transferred between H2 units paired up at equal distances from but on opposite sides of the chain center. All symmetric pairs of H2 units, not just the one for the chain ends, are included. This transfer is driven by the external electric field, and opposed by the chemical hardness of each H2 unit. Unlike the situation in a bulk solid, this charge transfer is not suppressed (or even much affected) by electrostatic interactions among the transferred charges for n≤7. Self-interaction-free approaches increase the chemical hardness of an H2 unit in comparison with semilocal density functionals, and so reduce the charge transfer. The physical picture behind the model is validated and its limitations are revealed by an analysis of the charge density from self-consistent electronic structure calculations. An appendix presents an accurate method to extract the hyperpolarizability from self-consistent calculations, and its results.",
author = "Adrienn Ruzsinszky and Perdew, {John P.} and G. Csonka",
year = "2008",
month = "8",
day = "15",
doi = "10.1103/PhysRevA.78.022513",
language = "English",
volume = "78",
journal = "Physical Review A - Atomic, Molecular, and Optical Physics",
issn = "1050-2947",
publisher = "American Physical Society",
number = "2",

}

TY - JOUR

T1 - Simple charge-transfer model to explain the electrical response of hydrogen chains

AU - Ruzsinszky, Adrienn

AU - Perdew, John P.

AU - Csonka, G.

PY - 2008/8/15

Y1 - 2008/8/15

N2 - Linear H2n chains of H2 units are experimentally unrealizable but simple and widely studied exemplars of the response coefficients (polarizabilities and hyperpolarizabilities) of polymer chains in uniform longitudinal electric fields. They show two surprising features: (1) Their response coefficients, unlike those of bulk solids, show a strong nonlinear dependence upon length or n. (2) Their response coefficients are seriously too large when computed with standard local or semilocal density functionals, but are much more correct when computed with self-interaction-free approaches (including Hartree-Fock). We propose a simple charge-transfer model which explains both of these effects in analytic terms. In this model, charge is transferred between H2 units paired up at equal distances from but on opposite sides of the chain center. All symmetric pairs of H2 units, not just the one for the chain ends, are included. This transfer is driven by the external electric field, and opposed by the chemical hardness of each H2 unit. Unlike the situation in a bulk solid, this charge transfer is not suppressed (or even much affected) by electrostatic interactions among the transferred charges for n≤7. Self-interaction-free approaches increase the chemical hardness of an H2 unit in comparison with semilocal density functionals, and so reduce the charge transfer. The physical picture behind the model is validated and its limitations are revealed by an analysis of the charge density from self-consistent electronic structure calculations. An appendix presents an accurate method to extract the hyperpolarizability from self-consistent calculations, and its results.

AB - Linear H2n chains of H2 units are experimentally unrealizable but simple and widely studied exemplars of the response coefficients (polarizabilities and hyperpolarizabilities) of polymer chains in uniform longitudinal electric fields. They show two surprising features: (1) Their response coefficients, unlike those of bulk solids, show a strong nonlinear dependence upon length or n. (2) Their response coefficients are seriously too large when computed with standard local or semilocal density functionals, but are much more correct when computed with self-interaction-free approaches (including Hartree-Fock). We propose a simple charge-transfer model which explains both of these effects in analytic terms. In this model, charge is transferred between H2 units paired up at equal distances from but on opposite sides of the chain center. All symmetric pairs of H2 units, not just the one for the chain ends, are included. This transfer is driven by the external electric field, and opposed by the chemical hardness of each H2 unit. Unlike the situation in a bulk solid, this charge transfer is not suppressed (or even much affected) by electrostatic interactions among the transferred charges for n≤7. Self-interaction-free approaches increase the chemical hardness of an H2 unit in comparison with semilocal density functionals, and so reduce the charge transfer. The physical picture behind the model is validated and its limitations are revealed by an analysis of the charge density from self-consistent electronic structure calculations. An appendix presents an accurate method to extract the hyperpolarizability from self-consistent calculations, and its results.

UR - http://www.scopus.com/inward/record.url?scp=49749092994&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=49749092994&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.78.022513

DO - 10.1103/PhysRevA.78.022513

M3 - Article

VL - 78

JO - Physical Review A - Atomic, Molecular, and Optical Physics

JF - Physical Review A - Atomic, Molecular, and Optical Physics

SN - 1050-2947

IS - 2

M1 - 022513

ER -