[CP2K-user] [CP2K:14294] Is there any basis set updating during Car–Parrinello molecular dynamics?

[Thomas Kühne]

Dear CC?, 

yes the basis functions are atom centered and hence move with the atoms causing 
that the overlap integrals needs to be recomputed whenever the positions are updated 
(e.g. geometry optimization, molecular dynamics, etc.). By default in CP2K ab-initio 
MD simulations are conducted by means of the Born-Oppenheimer scheme (the 
original CPMD method is not implemented), i.e. in every time-step a conventional 
electronic structure calculation is conducted. 
The de facto standard in CP2K are so-called „molecularly optimized“ basis set (aka 
MOLOPT basis), whose Gaussian exponents and contraction coefficients are optimized 
based on molecular systems using an objective function that is the sum of the total 
energy and the logarithm of the condition number of the overlap matrix. In this way, 
contrary to typical augmented basis sets, the overlap matrix is generally well conditioned, 
so that there are NO near linear dependencies in the basis, even for periodic systems!

Greetings, 
Thomas Kühne

> Am 26.11.2020 um 00:48 schrieb C C <wc0... at gmail.com>:
> 
> Hi,
> 
>  I have a very naive question. According to 
> https://www.cp2k.org/basis_sets
>  CP2K adopted atomic centered Gaussian.
> 
>  From what I understood, in CPMD calculation, the potential energy surface is calculated on the fly (not prior constructed). During the MD simulation, nuclei changed their positions and overlap integrals will change. Will CP2K update its basis, i.e., adjust the center of basis function? Is there any near dependence in the calculation?
> 
> Thank you very much!
> 
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==============================
Thomas D. Kühne
Dynamics of Condensed Matter
Chair of Theoretical Chemistry
University of Paderborn
Warburger Str. 100
D-33098 Paderborn
Germany
tdku... at mail.upb.de
+49/(0)5251/60-5726

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