[CPMD-list] linear response calculation

[Axel Kohlmeyer]

>>> "SB" == Salomon Billeter <ZRLSRB at ch.ibm.com> writes:

SB> Hi,

>> 1.) VIBRATIONAL ANALYSIS LR is currently broken (and has been for
>> quite some time). you can do a LINEAR RESPONSE calculation with
>> &RESP PHONON &END instead. check out the vibanal subdirectory
>> in the CPMD test suite.

SB> The default AUTOMATIC optimizer (switching between optimizers depending on
SB> the gradient) will run into troubles. However, if you are selecting the
SB> DIIS or the PCG optimizers to solve the LR equations, the code will run
SB> just fine and produce reasonable results in many cases. It's a good idea
SB> anyway to check and to add a section &LINRES ... &END instead of going with
SB> the defaults (like in the test examples methan*). I'll look into the

dear salomon,

i beg to differ here. defaults should be set to something that 
works, even if it is not very efficient. if one cannot produce
reasonable defaults, there should be a test in the code demanding 
additional input (e.g. a &LINRES section in the current example)
and specific instructions or at least some hints in the manual. 

how else should somebody find this out? there are far too many
documented (and undocumented) flags and options to try them out
systematically and in this case there have been no examples available.

best regards,
        axel.

SB> problems of AUTOMATIC when I find the time.

SB> Best regards,
SB> Salomon

SB> _______________________________________________
SB> CPMD-list mailing list
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SB> http://cpmd.org/mailman/listinfo/cpmd-list



--

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Axel Kohlmeyer       e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
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If you make something idiot-proof, the universe creates a better idiot.