At and mol further

Overview > O atom > O atom spinpolarized > O atom spinpolarized low symmetry > O dimer > CO > CO vibration > CO partial DOS > H2O > H2O vibration > H2O molecular dynamics > Further things to try  > List of tutorials

• How does the energy change when one decreases SIGMA to 0.001 in the INCAR file starting from the O_atom? Why?

• Try to copy CONTCAR to POSCAR after running the example O_dimer. Why is the calculation so fast?

• Try to play with the parameter POTIM for the example O_dimer. What is the optimal value?

• What is the reason for the imaginary frequency in the example CO_vibration? Does the behaviour improve when the step width (smaller or larger) is changed? Also try to improve the precision to which the ground state is converged (EDIFF=1E-5). What happens if the accuracy of the calculations is improved (PREC=Accurate}}).

• Try to use the conjugate gradient algorithm to the [math]\displaystyle{ \mathrm{H}_{2}\mathrm{O} }[/math] molecule (example H2O).

• Calculate the vibrational frequencies of the [math]\displaystyle{ \mathrm{H}_{2}\mathrm{O} }[/math] molecule (example H2O) after relaxation (example H2Ovib). Why does one find 3 modes that have small frequencies? Try EDIFF=1E-5 instead of EDIFF=1E-4.

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