VARBAS - abinit @ ウィキ

VARBAS

基本的な変数

acell

セルの大きさ(by Bohr, 1Bohr=0.5291772108Å, 1Å=1.889726Bohr)
基底ベクトルの長さを表していて、３つで１セット。

ecut

エネルギーカットオフ(by Bohr)
与えられたK点での平面波の波数をコントロールする運動エネルギーのカットオフ。
デフォルトの単位はHartree。
収束の計算には大きい値を用いるほうが良い。

iscf

自己撞着場サイクルを決める整数。
# =1 => get the largest eigenvalue of the SCF cycle
(DEVELOP option, used with irdwfk=1 or irdwfq=1)
# =2 => SCF cycle, simple mixing of the potential
# =3 => SCF cycle, Anderson mixing of the potential
# =4 => SCF cycle, Anderson mixing of the potential based on the two previous iterations
# =5 => SCF cycle, CG based on the minim. of the energy with respect to the potential
# =7 => SCF cycle, Pulay mixing of the potential based on the npulayit previous iterations
# =12 => SCF cycle, simple mixing of the density
# =13 => SCF cycle, Anderson mixing of the density
# =14 => SCF cycle, Anderson mixing of the density based on the two previous iterations
# =15 => SCF cycle, CG based on the minim. of the energy with respect to the density
# =17 => SCF cycle, Pulay mixing of the density based on the npulayit previous iterations
そのまま引用。デフォルトは7。

ixc

0=> NO xc;

1=> LDA or LSD, Teter Pade parametrization (4/93, published in S. Goedecker, M. Teter, J. Huetter, Phys.Rev.B54, 1703 (1996)), which reproduces Perdew-Wang (which reproduces Ceperley-Alder!).
2=> LDA, Perdew-Zunger-Ceperley-Alder (no spin-polarization)
3=> LDA, old Teter rational polynomial parametrization (4/91) fit to Ceperley-Alder data (no spin-polarization)
4=> LDA, Wigner functional (no spin-polarization)
5=> LDA, Hedin-Lundqvist functional (no spin-polarization)
6=> LDA, "X-alpha" functional (no spin-polarization)
7=> LDA or LSD, Perdew-Wang 92 functional
8=> LDA or LSD, x-only part of the Perdew-Wang 92 functional
9=> LDA or LSD, x- and RPA correlation part of the Perdew-Wang 92 functional

11=> GGA, Perdew-Burke-Ernzerhof GGA functional
12=> GGA, x-only part of Perdew-Burke-Ernzerhof GGA functional
13=> GGA potential of van Leeuwen-Baerends, while for energy, Perdew-Wang 92 functional
14=> GGA, revPBE of Y. Zhang and W. Yang, Phys. Rev. Lett. 80, 890 (1998)
15=> GGA, RPBE of B. Hammer, L.B. Hansen and J.K. Norskov, Phys. Rev. B 59, 7413 (1999)
16=> GGA, HTCH93 of F.A. Hamprecht, A.J. Cohen, D.J. Tozer, N.C. Handy, J. Chem. Phys. 109, 6264 (1998)
17=> GGA, HTCH120 of A.D. Boese, N.L. Doltsinis, N.C. Handy, and M. Sprik, J. Chem. Phys 112, 1670 (1998) - The usual HCTH functional.
18=> (NOT AVAILABLE : tentative assignment, for planning purposes) GGA, BLYP.
19=> (NOT AVAILABLE : tentative assignment, for planning purposes) GGA, BP.

20=> Fermi-Amaldi xc ( -1/N Hartree energy, where N is the number of electrons per cell ; G=0 is not taken into account however), for TDDFT tests. No spin-pol. Does not work for RF.
21=> same as 20, except that the xc-kernel is the LDA (ixc=1) one, for TDDFT tests.
22=> same as 20, except that the xc-kernel is the Burke-Petersilka-Gross hybrid, for TDDFT tests.
23=> GGA of Z. Wu and R.E. Cohen, Phys. Rev. 73, 235116 (2006).
26=> GGA, HTCH147 of A.D. Boese, N.L. Doltsinis, N.C. Handy, and M. Sprik, J. Chem. Phys 112, 1670 (1998).
27=> GGA, HTCH407 of A.D. Boese, and N.C. Handy, J. Chem. Phys 114, 5497 (2001).
28=> (NOT AVAILABLE : tentative assignment, for planning purposes) GGA, OLYP.

30=> (tentative assignment, for testing purposes) X-only functional, from the Nanoquanta libxc, developed by Miguel Marques
31=> (tentative assignment, for testing purposes) X+ VWN C functional, from the Nanoquanta libxc, developed by Miguel Marques
32=> (tentative assignment, for testing purposes) X+ PZ C functional, from the Nanoquanta libxc, developed by Miguel Marques
33=> (tentative assignment, for testing purposes) X+ PW C functional, from the Nanoquanta libxc, developed by Miguel Marques
34=> (tentative assignment, for testing purposes) X+ AMGB C functional, from the Nanoquanta libxc, developed by Miguel Marques

kpt

k点。デフォルトは原点。
ブリルアンゾーン中で対称性の良い点を特にk点と呼んでいる。

kptopt

k点の最適化。デフォルトは0
0=> read directly nkpt, kpt, kptnrm and wtk.
1=> rely on ngkpt or kptrlatt, as well as on nshiftk and shiftk to set up the k points. Take fully into account the symmetry to generate the k points in the Irreducible Brillouin Zone only.
(This is the usual mode for GS calculations)
2=> rely on ngkpt or kptrlatt, as well as on nshiftk and shiftk to set up the k points. Take into account only the time-reversal symmetry : k points will be generated in half the Brillouin zone.
(This is to be used when preparing or executing a RF calculation at q=(0 0 0) )
3=> rely on ngkpt or kptrlatt, as well as on nshiftk and shiftk to set up the k points. Do not take into account any symmetry : k points will be generated in the full Brillouin zone.
(This is to be used when preparing or executing a RF calculation at non-zero q )
4=> rely on ngkpt or kptrlatt, as well as on nshiftk and shiftk to set up the k points. Take into account all the symmetries EXCEPT the time-reversal symmetry to generate the k points in the Irreducible Brillouin Zone.
This has to be used when performing PAW calculations including spin-orbit coupling (pawspnorb/=0)
A negative value => rely on kptbounds, and ndivk to set up a band structure calculation along different lines (allowed only for iscf==-2). The absolute value of kptopt gives the number of segments of the band structure.

nband

電子が入る可能性のあるエネルギーバンドの最大値。
(この理解が正しいかどうかは怪しい）

ngkpt

サンプリングするｋ点をコントロールしている、基本グリッドの数。基底ベクトル方向で３セットの値を必要とする。
2×2×2の格子点が欲しければ
ngkpt 2 2 2
となる。

nkpt

ngkptから導かれるサンプリングするk点の数。

nshiftk

nstep

SCFサイクルのステップの数。
デフォルトは30。

ntypat

元素の数。

occopt

rprim

セルのベクトルの方向。３個の３次元ベクトルが必要。

shiftk

toldfe

toldff

typat

元素の種類。znuclで指定した元素番号の並び順で1,2,3…となっている。

xangst

Åでの直交系での初期原子座標。

xcart

Bohrでの直交系での初期原子座標。

xred

セルの基本ベクトルを１とした場合の初期原子座標。

znucl

計算する元素の原子番号。