calculation of oscillator strength

Dear MRCC Developers,

I am trying to calculate oscillator strenth in CCLRT method.My MINP file looks like following

# LR-CCSD transition moment calculation for the lowest B3u excited state of ethylene with the cc-pVDZ basis set
basis=PVDZ
calc=CCSD
mem=10000MB
nsing=3
dens=6
symm=B2

geom=xyz
3

H -0.756940 -0.520501 0.000000
H 0.756940 -0.520501 0.000000
O 0.000000 0.065584 0.000000

My job is getting terminated with the following error

======================================================================

Calculation of the <0|(1+L)[exp(-T) H exp(T), dT/dx]|K> term...

Calculation of the <0|(1+L)[exp(-T){p+q-}exp(T), dT/dx]|0> term...

======================================================================



======================================================================



Fatal error in xmrcc.
Program will stop.

************************ 2014-11-17 17:21:39 *************************
Error at the termination of mrcc.
**********************************************************************
======================================================================

However, if I just remove the dens=6, the job is running fine. But I am also interested in the oscillator strength of the second and higher excited state of that symmetry.
I am using a pre-compiled version of MRCC and running in standalone mode.

Any advice will be of great help.

With best regards,
achintya

Dear Achintya,
Oscillator strength calculations can be performed for only one excited state at a time, that is, nsing=2 is the only option. Sorry, this is not mentioned in the manual, and the error message is also not informative, we will fix it.
The get the oscillators strength for a higher excited state you need to converge the LRCC equations to that root. The best practice is to run a calculation with the desired number of excited states, and then restart the calculation selecting the higher solutions (see the description of keyword rest in the manual. That is, first run a calculation with the following MINP file:

basis=cc-pVDZ
calc=CCSD
mem=5000MB
nsing=3
symm=B2

geom=xyz
3

H -0.756940 -0.520501 0.000000
H 0.756940 -0.520501 0.000000
O 0.000000 0.065584 0.000000

Then with the following one:

basis=cc-pVDZ
calc=CCSD
mem=5000MB
nsing=2
dens=6
symm=B2
rest=3
1 3
diag=follow

geom=xyz
3

H -0.756940 -0.520501 0.000000
H 0.756940 -0.520501 0.000000
O 0.000000 0.065584 0.000000

In this way you will get the osc. strength for the third root of B2 symmetry. Note that at the first calculation you can also use a lower level method, that is, calc=CCS.

Dear Prof. Kallay,

Its working fine.
Thank you for your kind attention.
With best regards,
achintya