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General Questions and Answers / Re: Silicene bandstructure calculation
« on: December 29, 2011, 07:24 »
Hi,
I have generated a planar geometry of silicene by optmizing only the x and y directions (left out the 'z' coordinate by checking its box).The LDA/GGA DFT calculations for lattice parameter and the bond length of Si-Si matches with the literature i have read.See the image attached.The 'c' parameter was kept large so that inter layer interactions are minnimum and a isolated 2d geometry is obtained.Now i don't want to change the bond length and make the atoms out of plane ..for this i need to roate one of the atoms while keeping the other fixed at origin. Although i know how rotation is performed about an axis i am confused ..which axis i should choose to roatate .. 'y' or 'xy' can you suggest this by looking at the geometry???.Also rotation in steps of 0.5 or 1 degree can be performed to give whole list of required cartesian coordinates for calculating energy at each point... i want to know is there an inbuilt rotation class or function rotate() which i can use in the code to run through the points or i have to rely on GUI only.
OR... i should drop the idea of rotating and perfom optimization only in 'z' direction for the atom lying away from d origin.. by choosing very less force something like 0.0002 ev/A.. also do i need to keep both stress and forces low??? or only 'force' needs to kept low..leaving the stress at default This way i would get the buckling parameter in theory.
I have generated a planar geometry of silicene by optmizing only the x and y directions (left out the 'z' coordinate by checking its box).The LDA/GGA DFT calculations for lattice parameter and the bond length of Si-Si matches with the literature i have read.See the image attached.The 'c' parameter was kept large so that inter layer interactions are minnimum and a isolated 2d geometry is obtained.Now i don't want to change the bond length and make the atoms out of plane ..for this i need to roate one of the atoms while keeping the other fixed at origin. Although i know how rotation is performed about an axis i am confused ..which axis i should choose to roatate .. 'y' or 'xy' can you suggest this by looking at the geometry???.Also rotation in steps of 0.5 or 1 degree can be performed to give whole list of required cartesian coordinates for calculating energy at each point... i want to know is there an inbuilt rotation class or function rotate() which i can use in the code to run through the points or i have to rely on GUI only.
OR... i should drop the idea of rotating and perfom optimization only in 'z' direction for the atom lying away from d origin.. by choosing very less force something like 0.0002 ev/A.. also do i need to keep both stress and forces low??? or only 'force' needs to kept low..leaving the stress at default This way i would get the buckling parameter in theory.
