LR-TDDFT roots problem

[Elious]

Hi,

I am trying to calculate the singlet excited state roots of ethylene at its optimized geometry using LR-TDDFT in NWCHEM-7.0.0. When I specified to calculate 1 root, it gives a root at 9.0564 eV, but when I did a calculation for 5 roots, this root comes out to be the 2nd root. Can you explain this? and when should I be careful to look out for such problems?

Thanks

Elious

[Niri Govind]

Hi Elious,

I am not sure I understand. Can you post your input file ?

Thanks.

Best,

-Niri 

Niri Govind

PNNL

niri....@pnnl.gov

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[Elious]

Hi Niri,

Here is the attached input:

start eth_1_root
echo
title "eth_1_root"
memory 1024 mb
geometry units au nocenter noautoz noautosym
C   4.80345558032834e-01  2.74784910166158e-01 -9.93550295230338e-05
C   2.99444680733594e+00  3.45997970273821e-01  9.99309120519461e-05
H  -5.61420965738096e-01 -1.26948111451164e+00 -8.67738492252634e-01
H  -6.46827328295874e-01  1.75791090024784e+00  8.67773679089603e-01
H   4.12159507882946e+00 -1.13715393418578e+00 -8.67771077013657e-01
H   4.03619411515936e+00  1.89028512701509e+00  8.67735314294173e-01
END

BASIS
 * library 6-31g*
END

DFT
xc b3lyp
direct
END

TDDFT
 nroots 1
 cis
 singlet
 notriplet
 maxiter 250
END

TASK TDDFT ENERGY

This gives me 1 singlet root at 9.0564 eV. But when I change the nroots = 5, I get 5 singlet roots at: 8.4847 eV, 9.0564 eV, 9.2567 eV, 9.5424 eV, 9.8700 eV. So the excited state at nroots =1 comes out to be the second excited state when nroots=5.

Thanks,

Elious