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Alternative separation of exchange and correlation in density-functional theory
KTH, Superseded Departments, Physics.
Compl. Mat. and Molecular Biology, Sandia National Laboratories, Albuquerque.
2003 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 68, no 24, 2451201-2451205 p.Article in journal (Refereed) Published
Abstract [en]

It has recently been shown that local values of the conventional exchange energy per particle cannot be described by an analytic expansion in the density variation. Yet, it is known that the total exchange-correlation (XC) energy per particle does not show any corresponding nonanalyticity. Indeed, the nonanalyticity is here shown to be an effect of the separation into conventional exchange and correlation. We construct an alternative separation in which the exchange part is made well behaved by screening its long-ranged contributions, and the correlation part is adjusted accordingly. This alternative separation is as valid as the conventional one, and introduces no new approximations to the total XC energy. We demonstrate functional development based on this approach by creating and deploying a local-density-approximation-type XC functional. Hence, this work includes both the theory and the practical calculations needed to provide a starting point for an alternative approach towards improved approximations of the total XC energy.

Place, publisher, year, edition, pages
2003. Vol. 68, no 24, 2451201-2451205 p.
Keyword [en]
article, calculation, correlation analysis, density functional theory, elementary particle, energy, mathematical analysis, screening
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-6786DOI: 10.1103/PhysRevB.68.245120ISI: 000188391900043OAI: oai:DiVA.org:kth-6786DiVA: diva2:11595
Note
QC 20100831Available from: 2005-09-23 Created: 2005-09-23 Last updated: 2017-12-14Bibliographically approved
In thesis
1. The many-electron energy in density functional theory: from exchange-correlation functional design to applied electronic structure calculations
Open this publication in new window or tab >>The many-electron energy in density functional theory: from exchange-correlation functional design to applied electronic structure calculations
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [sv]

Att förutsäga egenskaper hos material och kemiska system är en viktig komponent för teoretisk och teknisk utveckling i fysik, kemi och biologi. Ett systems egenskaper styrs till stor del av dess elektrontillstånd. Datorprogram som baseras på täthetsfunktionalsteori kan beskriva elektronkonfigurationer mycket noggrant. Täthetsfunktionalsteorin hanterar all kvantmekanisk energi exakt, förutom ett mindre bidrag, utbytes-korrelationsenergin. Avhandlingen diskuterar existerande approximationer av utbytes-korrelationsenergin och presenterar en ny metod för konstruktion av funktionaler som hanterar detta bidrag---delsystems-funktionalmetoden. Flera teoretiska resultat relaterade till funktionalutveckling ges. En utbytes-korrelations-funktional har konstruerats helt utan empiriska antaganden (dvs, från första-princip). Funktionalen har använts för att beräkna gitterkonstant, bulkmodul och vakansenergi för aluminium, platina och kisel. Arbetet förväntas vara generellt tillämpbart inom området för täthetsfunktionalsteoriberäkningar

Abstract [en]

The prediction of properties of materials and chemical systems is a key component in theoretical and technical advances throughout physics, chemistry, and biology. The properties of a matter system are closely related to the configuration of its electrons. Computer programs based on density functional theory (DFT) can calculate the configuration of the electrons very accurately. In DFT all the electronic energy present in quantum mechanics is handled exactly, except for one minor part, the exchange-correlation (XC) energy. The thesis discusses existing approximations of the XC energy and presents a new method for designing XC functionals---the subsystem functional scheme. Numerous theoretical results related to functional development in general are presented. An XC functional is created entirely without the use of empirical data (i.e., from so called first-principles). The functional has been applied to calculations of lattice constants, bulk moduli, and vacancy formation energies of aluminum, platinum, and silicon. The work is expected to be generally applicable within the field of computational density functional theory.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. ix, 85 p.
Series
Trita-FYS, ISSN 0280-316X ; 2005:48
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-428 (URN)91-7178-150-1 (ISBN)
Public defence
2005-09-30, Sal FR4, AlbaNova, Roslagstullsbacken 21, Stockholm, 14:00
Opponent
Supervisors
Note
QC 20100830Available from: 2005-09-23 Created: 2005-09-23 Last updated: 2010-08-31Bibliographically approved

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