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Operator-based truncation scheme based on the many-body fermion density matrix

หน่วยงาน Nanyang Technological University, Singapore

รายละเอียด

ชื่อเรื่อง : Operator-based truncation scheme based on the many-body fermion density matrix
นักวิจัย : Cheong, Siew Ann , Henley, Christopher L.
คำค้น : DRNTU::Science::Physics::Atomic physics::Solid state physics
หน่วยงาน : Nanyang Technological University, Singapore
ผู้ร่วมงาน : -
ปีพิมพ์ : 2547
อ้างอิง : Cheong, S. A., & Henley, C. L. (2004). Operator-based truncation scheme based on the many-body fermion density matrix. Physical Review B., 69(7), 1-20. , 0163-1829 , http://hdl.handle.net/10220/4601 , http://sfxna09.hosted.exlibrisgroup.com:3410/ntu/sfxlcl3?sid=metalib:ISI_WOS_XML&id=doi:&genre=&isbn=&issn=1098-0121&date=2004&volume=69&issue=7&spage=&epage=&aulast=Cheong&aufirst=%20SA&auinit=SA&title=PHYSICAL%20REVIEW%20B&atitle=Operator%2Dbased%20truncation%20scheme%20based%20on%20the%20many%2Dbody%20fermion%20density%20matrix , http://dx.doi.org/10.1103/PhysRevB.69.075112
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : Physical review B
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

In an earlier work [S. A. Cheong and C. L. Henley, preceding paper], we derived an exact formula for the many-body density matrix ρ B of a block of B sites cut out from an infinite chain of noninteracting spinless fermions, and found that the many-particle eigenvalues and igenstates of ρ B can all be constructed out of the one-particle eigenvalues and one-particle eigenstates, respectively. In this paper we improved upon this understanding, and developed a statistical-mechanical analogy between the density-matrix eigenstates and the many-body states of a system of noninteracting fermions. Each density-matrix eigenstate corresponds to a particular set of occupation of single-particle pseudo-energy levels, and the density-matrix eigenstate with the largest weight, having the structure of a Fermi sea ground state, unambiguously defines a pseudo-Fermi level. Based on this analogy, we outlined the main ideas behind an operator-based truncation of the density-matrix eigenstates, where single-particle pseudo-energy levels far away from the pseudo-Fermi level are removed as degrees of freedom. We report numerical evidence for scaling behaviors in the single-particle pseudo-energy spectrum for different block sizes B and different filling fractions n. With the aid of these scaling relations, which tell us that the block size B plays the role of an inverse temperature in the statistical-mechanical description of the density-matrix eigenstates and eigenvalues, we looked into the performance of our operator-based truncation scheme in minimizing the discarded density-matrix weight and the error in calculating the dispersion relation for elementary excitations. This performance was compared against that of the traditional density-matrix-based truncation scheme, as well as against an operator-based plane-wave truncation scheme, and found to be very satisfactory.

บรรณานุกรม :
Cheong, Siew Ann , Henley, Christopher L. . (2547). Operator-based truncation scheme based on the many-body fermion density matrix.
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Cheong, Siew Ann , Henley, Christopher L. . 2547. "Operator-based truncation scheme based on the many-body fermion density matrix".
    กรุงเทพมหานคร : Nanyang Technological University, Singapore.
Cheong, Siew Ann , Henley, Christopher L. . "Operator-based truncation scheme based on the many-body fermion density matrix."
    กรุงเทพมหานคร : Nanyang Technological University, Singapore, 2547. Print.
Cheong, Siew Ann , Henley, Christopher L. . Operator-based truncation scheme based on the many-body fermion density matrix. กรุงเทพมหานคร : Nanyang Technological University, Singapore; 2547.