Sample directory: band/CnHn/
This example illustrates how a one-dimensional periodic system can be treated by specifying only one lattice vector. It further shows how variables can be defined with the DEFINE keyword. The rest more or less speaks for itself. The Kspace integration is taken very accurate, whereas real space integration (ACCURACY keyword) is not so accurate.
Here and in the following BAND examples, we will leave out some space consuming parts of the input file which have been discussed already. Please check the actual input files if you wish to repeat one of the calculations.
$ADFBIN/band << eor Title Polymer Comment Technical Quadratic k space integration (1D) Low real space integration accuracy Definitions of variables Features Lattice : 1D, polymer Unit cell : 4 atoms Basis : NO+STO w/ core End Kspace 5 Accuracy 3 Units Length Angstrom Angle Radian End Define dCCd=1.3386 dCCs=1.4510 dCH=1.0770 aCCC=124.5/180*pi arC=aCCC-pi/2 aCCH=119.2/180*pi ! double bonded CC arH=aCCH-pi/2 End Lattice dCCd+sin(arC)*dCCs cos(arC)*dCCs 0.0 End Atoms C dCCd/2 0.0 0.0 -dCCd/2 0.0 0.0 End Atoms H dCCd/2+sin(arH)*dCH -cos(arH)*dCH 0.0 -dCCd/2-sin(arH)*dCH cos(arH)*dCH 0.0 End
A larger unit cell can of course be specified as well. In the second part of the example a supercell of 5 units is used. Another new feature introduced in this example is the TAILS keyword, which similar to ADF implies that distance cut-offs are applied to make the calculation cheaper. At the moment no big gains are yet to be expected from this, but this situation is expected to change in future versions of the code.
in the BASIS key. This subkey is actually mandatory at the moment if the TAILS keyword is used.
$ADFBIN/band << eor Title Polymer with big unit cell (5 units) Comment Technical Low quadratic k space integration (1D) Low real space integration accuracy Definitions of variables Features Lattice : 1D, polymer Unit cell : 4 atoms Basis : NO+STO w/ core End Kspace 3 Accuracy 3 Units Length Angstrom Angle Radian End Tails Bas=1E-2 Define dCCd=1.3386 dCCs=1.4510 dCH=1.0770 aCCC=124.5/180*pi arC=aCCC-pi/2 aCCH=119.2/180*pi ! double bonded CC arH=aCCH-pi/2 Latx(nlatt)=nlatt*(dCCd+sin(arC)*dCCs) Laty(nlatt)=nlatt*(cos(arC)*dCCs) Laty(nlatt)=nlatt*(cos(arC)*dCCs) End Lattice Latx(5) Laty(5) 0.0 End Atoms C dCCd/2 0.0 0.0 -dCCd/2 0.0 0.0 dCCd/2+Latx(1) Laty(1) 0.0 -dCCd/2+Latx(1) Laty(1) 0.0 dCCd/2+Latx(2) Laty(2) 0.0 -dCCd/2+Latx(2) Laty(2) 0.0 dCCd/2+Latx(3) Laty(3) 0.0 -dCCd/2+Latx(3) Laty(3) 0.0 dCCd/2+Latx(4) Laty(4) 0.0 -dCCd/2+Latx(4) Laty(4) 0.0 End Atoms H dCCd/2+sin(arH)*dCH -cos(arH)*dCH 0.0 -dCCd/2-sin(arH)*dCH cos(arH)*dCH 0.0 dCCd/2+sin(arH)*dCH+Latx(1.0) -cos(arH)*dCH+Laty(1.0) 0.0 -dCCd/2-sin(arH)*dCH+Latx(1.0) cos(arH)*dCH+Laty(1.0) 0.0 dCCd/2+sin(arH)*dCH+Latx(2.0) -cos(arH)*dCH+Laty(2.0) 0.0 -dCCd/2-sin(arH)*dCH+Latx(2.0) cos(arH)*dCH+Laty(2.0) 0.0 dCCd/2+sin(arH)*dCH+Latx(3.0) -cos(arH)*dCH+Laty(3.0) 0.0 -dCCd/2-sin(arH)*dCH+Latx(3.0) cos(arH)*dCH+Laty(3.0) 0.0 dCCd/2+sin(arH)*dCH+Latx(4.0) -cos(arH)*dCH+Laty(4.0) 0.0 -dCCd/2-sin(arH)*dCH+Latx(4.0) cos(arH)*dCH+Laty(4.0) 0.0 End
