[CPMD-list] Output of TDDFT geometry optimisation

[Latévi Max LAWSON DAKU]

Dear CPMD users and developers,

Using the CPMD code - to which I am quite new, I am trying to carry
out a constrained geometry optimization in the first excited state,
within TDA-TDDFT. I used the following input in an attempt I made:

    &CPMD
      RESTART WAVEFUNCTION COORDINATES LINRES
      OPTIMIZE GEOMETRY
      LBFGS
      TDDFT
      CONVERGENCE ORBITALS
      1.0d-7
      STORE
      40
      STRUCTURE BONDS ANGLES DIHEDRALS
    &END

    &TDDFT
      STATES SINGLET
      2
      TAMM-DANCOFF
      DAVIDSON PARAMETER
      150 1.D-7 50
      DAVIDSON RDIIS
      100 15 1.D-3
      FORCE STATE
      1
      TD_METHOD_A SAOP
    &END

    &DFT
      FUNCTIONAL PBE
      LR KERNEL LDA
    &END

The calculation ended normally but there are things I do not
understand in the output.
First, it seems that the job has stopped too early since, as this
can seen below, GNMAX is well above the convergence criterion
of 5e-4 :

     ****************************************************************
     *** TOTAL STEP NR.   431           GEOMETRY STEP NR.     20  ***
     *** GNMAX=  9.191471E-02 [3.81E-06]     ETOT=    -61.317526  ***
     *** GNORM=  1.687789E-02               DETOT=    -1.500E-07  ***
     *** CNSTR=  8.773584E-02                TCPU=       1305.02  ***
     ****************************************************************
     ================================================================
     =              END OF GEOMETRY OPTIMIZATION                    =
     ================================================================


Please note that the geometry really did no more significantly  evolve
during the last steps of the calculations. Maybe I missed the fact that
the convergence criteria are different for ground- and excited-state
optimizations ?! By the way, what does mean the number in brackets
that follows GNMAX ?

Secondly, I am not sure about the manner in which the ground-state
total energy is being evaluated during the calculation. In a given
calculation step, before solving the TDDFT eigenvalue problem, the
ground state is characterised first:

       1  3.028E-07   3.690E-08     -90.367734   -2.523E-06      4.82
       2  1.745E-07   1.342E-08     -90.367734   -8.812E-10      4.85
       3  1.514E-07   7.063E-09     -90.367734   -7.759E-11      5.00
       4  1.454E-07   3.517E-09     -90.367734   -2.143E-11      5.02
       5  1.167E-07   2.133E-09     -90.367734   -7.560E-12      5.05
       6  5.499E-08   1.536E-09     -90.367734   -3.382E-12      5.07
     ================================================================
     ==            DAVIDSON DIAGONALISATION OF TDDFT MATRIX        ==
     ================================================================

I expect that the SAOP potential is being used to determine the
KS eigensystem and that the energy which is reported (here, -90.367734 au)
is a post-SCF result obtained with the PBE functional. Is this correct ?

Then, after that the TDDFT forces have been computed, one ends up
with the following result for the energy (last calculation step), which
I would like to understand (for instance, no X-C contribution ??):

     (K+E1+L+N+X)                 TOTAL ENERGY =          -61.31752565 A.U.
     (K)                                    KINETIC  ENERGY =           
3.82987466 A.U.
     (E1=A-S+R)      ELECTROSTATIC  ENERGY =          -75.96854907 A.U.
     (S)                                                        ESELF
=           81.11826368 A.U.
    (R)                                                             ESR
=            4.43642281 A.U.
     (L)    LOCAL PSEUDOPOTENTIAL ENERGY =          -62.20759089 A.U.
     (N)          N-L PSEUDOPOTENTIAL ENERGY =            8.97368637 A.U.
     (X)      EXCHANGE-CORRELATION ENERGY =             .00000000 A.U.
                   GRADIENT CORRECTION ENERGY =              .00000000 A.U.
     (E)                EXCITATION ENERGY(TDDFT) =              
3.074333 e.V.


Could someone explain me what is the reported energy referring to ?
Besides digging into the code, which papers can help me understand
what is going on ?

Thanks in advance for your answers.

Best regards,
Max

-- 
***********************************************
Latevi Max LAWSON DAKU
Departement de chimie physique 
Universite de Geneve - Sciences II
30, quai Ernest-Ansermet  
CH-1211 Geneve 4 
Switzerland 

Tel: (41) 22/379 6548 ++ Fax: (41) 22/379 6103
***********************************************