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Tanvir ur Rahman Chowdhury
May 5, 2021, 3:23:42 PM5/5/21
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Hello,
I am new to NWChem. I have to compute the energies of some simple atoms like C, and O with the broken-symmetry densities. I am not sure how to write the dft part of the code. A typical NWChem code that I think will work might look like this -
echo
title "carbon atom"
start carbon_sym
geometry
C 0.0 0.0 0.0
end
basis
* library aug-cc-pvdz
end
dft
grid xfine
convergence energy 1d-8
xc scan
end
task dft energy
Thanks in advance.
Edoardo Aprà
May 5, 2021, 3:52:53 PM5/5/21
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Could you please clarify what you mean by "broken-symmetry density" for atoms? I am used to the definition of broken-symmetry electronic structure approaches for molecules containing more than one atom, but I cannot understand the concept of broken-symmetry solutions for atoms.
Tanvir ur Rahman Chowdhury
May 5, 2021, 4:05:55 PM5/5/21
to NWChem Forum
Hello Edoardo,
Thank you. Sorry for the mistake. I think to say I meant simple molecules like C2 and O2.
echo
title "carbon atom"
start carbon_sym
geometry
C 0.0 0.0 0.0
C 0.0 0.0 1.243
end
basis
* library aug-cc-pvdz
end
dft
grid xfine
convergence energy 1d-8
xc (some xc)
end
task dft energy
Edoardo Aprà
May 5, 2021, 4:10:34 PM5/5/21
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This topic has already been a few times in the forum. The previous postings should contain enough material to help preparing your input file.
Tanvir ur Rahman Chowdhury
May 18, 2021, 3:22:35 PM5/18/21
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Hello,
I looked into the links and prepared my input file. However, I am getting errors in the output file. Alternatively, I also tried simply turning off the sym and adapt in the DFT module. But that gives me almost the same DFT energy as the one with keeping sym and adapt on. I would really appreciate any tips/assistance.
Thanks in advance.
*****************************
First Attempt
echo
title "boron_mol"
start B_mol
geometry big
B 0.0 0.0 0.0
B 0.0 0.0 1.59
end
geometry b1
B 0.0 0.0 0.0
end
geometry b2
B 0.0 0.0 1.59
end
basis
* library 6-311++G(3df,3pd)
end
charge 0
set geometry b1
dft
odft
mult 2
xc scan
vectors input atomic output b1.mos
end
task dft ignore
charge 0
set geometry b2
dft
odft
mult 0
vectors input atomic output b2.mos
end
task dft ignore
charge 0
set geometry big
dft
odft
mult 3
grid xfine
convergence energy 1d-8
vectors input fragment b1.mos b2.mos output big.mos
iterations 100
end
task dft
**********************************************
Second Attempt
echo
title "boron_mol"
start B_mol
geometry
B 0.0 0.0 0.0
B 0.0 0.0 1.59
end
basis
* library 6-311++G(3df,3pd)
end
dft
odft
mult 3
grid xfine
convergence energy 1d-8
iterations 100
xc scan
sym off
adapt off
end
task dft
****************************************
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