MD-NPT REPORT Outputs

[reza_namakian1]

Dear VASP Team,

I was unable to find detailed explanations of the outputs in the REPORT file for an MD-NPT simulation. I would greatly appreciate it if someone could clarify exactly what the values after`t_b` and `p_b` keywords refer to in the REPORT file. Below, I have included an example from my REPORT file for your reference.

Thank you!

MDALGO = 3
LANGEVIN_GAMMA = 10.000 10.000 10.000 10.000 10.000
LANGEVIN_GAMMA_L = 10.000
SCALING = 0
CNEXP = 9.000 14.000
PMASS = 10.00000
LATTICE_CONSTRAINTS = T T T (X,Y,Z) = 9 degree(s) of freedom
EQUI_REGIME = 0
SHAKEMAXITER = 1000
SHAKETOL = 0.100000E-04
SHAKETOLSOFT = 0.100000E-04
SHAKESCA = 2.00000000
RANDOM_SEED = 781594578 0 0

original number of atomic DOF: 612
number of independent constraints: 4
number of active DOF: 608

========================================
MD step No. 1
========================================

RATTLE_vel converged in 3 steps

>Const_vel
cv> LA -0.207326E-18
cv> LA 0.000000E+00
cv> LA -0.468712E-20
cv> LR -0.525679E-21

RATTLE_vel converged in 3 steps

>Const_vel
cv> LA 0.209288E-18
cv> LA -0.203288E-19
cv> LA -0.172076E-19
cv> LR -0.272959E-19

RATTLE_vel converged in 3 steps

>Const_vel
cv> LA -0.584292E-19
cv> LA -0.169407E-19
cv> LA -0.274308E-19
cv> LR -0.272984E-19

RATTLE_pos converged in 7 steps

>Const_coord
cc> LA 1.57079 1.57079 -0.417152E-05
cc> LA 1.57080 1.57079 -0.179057E-05
cc> LA 1.57079 1.57080 0.102855E-05
cc> LR 81.80555 81.80555 -0.215885E-05

p_b> 0.000 1.089 1.445 2.534

t_b> 300.000 309.741 193.957 308.063

>Energies
E_tot E_pot E_kin EPS ES
e_b> -0.97431969E+03 -0.98256254E+03 0.82428482E+01 0.00000000E+00 0.00000000E+00

RANDOM_SEED = 781594578 1242 0

[michael_wolloch]

Dear reza_namakian1,

the lines containing "p_b>" and "t_b>" are written in the REPORT file for the Langevin thermostat when ISIF = 3. The values correspond to (in order):

p_b:

1. external pressure

2. instantaneous static pressure

3. instantaneous kinetic pressure

4. total instantaneous pressure (sum of 2 and 3)

t_b:

1. desired current temperature

2. atomic temperature at time slice t

3. lattice temperature at time slice t

4. total temperature at time slice t, taking the kinetic energy of the atoms and the lattice into account

Please refer to the source file src/dynconstr.F, specifically subroutine STEP_LANGEVIN_ISIF3 for information about how these quantities are calculated.

Let me know if that answers your question, so I can lock the topic,
Michael

[reza_namakian1]

Thanks a lot Michael!

That is very clear to me now.