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<TITLE>SUSPICIOUS: Pressure scaling ... </TITLE>
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<P><FONT SIZE=2 FACE="Arial">Dear ALL:</FONT>
<BR><FONT SIZE=2 FACE="Arial">I'm running (or trying to run) a MD with the following .mdp file ( s system composed of 10 different ions)</FONT>
<BR><FONT SIZE=2 FACE="Arial">A room temperature and 1 bar:</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; VARIOUS PREPROCESSING OPTIONS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">title = My Structure</FONT>
<BR><FONT SIZE=2 FACE="Courier New">cpp = /lib/cpp</FONT>
<BR><FONT SIZE=2 FACE="Courier New">include = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">define = </FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; RUN CONTROL PARAMETERS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">integrator = md</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; start time and timestep in ps = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">tinit = 0.0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">dt = 0.002</FONT>
<BR><FONT SIZE=2 FACE="Courier New">nsteps = 60000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; number of steps for center of mass motion removal = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstcomm = 1</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; OUTPUT CONTROL OPTIONS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Output frequency for coords (x), velocities (v) and forces (f) = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstxout = 5000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstvout = 5000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstfout = 0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Output frequency for energies to log file and energy file = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstlog = 1000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstenergy = 1000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Output frequency and precision for xtc file = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstxtcout = 5000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">xtc_precision = 5000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; This selects the subset of atoms for the xtc file. You can = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; select multiple groups. By default all atoms will be written. = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">xtc-grps = Si O Al B Mg Ca Ba Sr As Na </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Selection of energy groups = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">energygrps = Si O Al B Mg Ca Ba Sr As Na </FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; NEIGHBORSEARCHING PARAMETERS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; nblist update frequency = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstlist = 10</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; ns algorithm (simple or grid) = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">ns_type = grid</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Periodic boundary conditions: xyz or none = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">pbc = xyz</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; nblist cut-off = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;rlist = 1.5</FONT>
<BR><FONT SIZE=2 FACE="Courier New">rlist = 0.75</FONT>
<BR><FONT SIZE=2 FACE="Courier New">domain-decomposition = no</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; OPTIONS FOR ELECTROSTATICS AND VDW = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Method for doing electrostatics = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">coulombtype = Cut-off</FONT>
<BR><FONT SIZE=2 FACE="Courier New">rcoulomb_switch = 0.0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">;rcoulomb = 1.8</FONT>
<BR><FONT SIZE=2 FACE="Courier New">rcoulomb = 0.8</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Dielectric constant (DC) for cut-off or DC of reaction field = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">epsilon_r = 20 </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Method for doing Van der Waals = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">vdw_type = Cut-off</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; cut-off lengths = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">rvdw_switch = 0.9</FONT>
<BR><FONT SIZE=2 FACE="Courier New">;rvdw = 1.8</FONT>
<BR><FONT SIZE=2 FACE="Courier New">rvdw = 0.8</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Apply long range dispersion corrections for Energy and Pressure = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">DispCorr = No</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Spacing for the PME/PPPM FFT grid = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">fourierspacing = 0.12</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; FFT grid size, when a value is 0 fourierspacing will be used = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">fourier_nx = 10</FONT>
<BR><FONT SIZE=2 FACE="Courier New">fourier_ny = 10</FONT>
<BR><FONT SIZE=2 FACE="Courier New">fourier_nz = 10</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; EWALD/PME/PPPM parameters = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">pme_order = 4</FONT>
<BR><FONT SIZE=2 FACE="Courier New">ewald_rtol = 1e-05</FONT>
<BR><FONT SIZE=2 FACE="Courier New">epsilon_surface = 0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">optimize_fft = no</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; OPTIONS FOR WEAK COUPLING ALGORITHMS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Temperature coupling = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">tcoupl = Berendsen</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Groups to couple separately = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">tc-grps = SiG O Al B Mg Ca Ba Sr As Na </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Time constant (ps) and reference temperature (K) = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">tau_t = 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">ref_t = 300.0 300.0 300.0 300.0 300.0 300.0 300.0 300.0 300.0 300.0</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; Pressure coupling = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">Pcoupl = Berendsen</FONT>
<BR><FONT SIZE=2 FACE="Courier New">Pcoupltype = Isotropic</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Time constant (ps), compressibility (1/bar) and reference P (bar) = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">tau_p = 25.0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">;compressibility = 2.5E-7 </FONT>
<BR><FONT SIZE=2 FACE="Courier New">compressibility = 9.804E-7 </FONT>
<BR><FONT SIZE=2 FACE="Courier New">ref_p = 1.0</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; SIMULATED ANNEALING CONTROL = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">annealing = no no no no no no no no no no</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Time at which temperature should be zero (ps) = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;zero_temp_time = 0</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; GENERATE VELOCITIES FOR STARTUP RUN = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">gen_vel = yes</FONT>
<BR><FONT SIZE=2 FACE="Courier New">gen_temp = 300.0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">gen_seed = 473529</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; OPTIONS FOR BONDS = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">constraints = none </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Type of constraint algorithm = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">constraint_algorithm =</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Do not constrain the start configuration = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">unconstrained_start = no</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Relative tolerance of shake = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">shake_tol = 0.0001</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Highest order in the expansion of the constraint coupling matrix = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">lincs_order = 4</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Lincs will write a warning to the stderr if in one step a bond = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">; rotates over more degrees than = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">lincs_warnangle = 30</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Convert harmonic bonds to morse potentials = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">morse = no</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; NMR refinement stuff = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Distance restraints type: No, Simple or Ensemble = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">disre = No</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Force weighting of pairs in one distance restraint: Equal or Conservative = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">disre_weighting = Equal</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Use sqrt of the time averaged times the instantaneous violation = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">disre_mixed = no</FONT>
<BR><FONT SIZE=2 FACE="Courier New">disre_fc = 1000</FONT>
<BR><FONT SIZE=2 FACE="Courier New">disre_tau = 1.25</FONT>
<BR><FONT SIZE=2 FACE="Courier New">; Output frequency for pair distances to energy file = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">nstdisreout = 100</FONT>
</P>
<P><FONT SIZE=2 FACE="Courier New">; Free energy control stuff = </FONT>
<BR><FONT SIZE=2 FACE="Courier New">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
<BR><FONT SIZE=2 FACE="Courier New">free_energy = no</FONT>
<BR><FONT SIZE=2 FACE="Courier New">init_lambda = 0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">delta_lambda = 0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">sc-alpha = 0</FONT>
<BR><FONT SIZE=2 FACE="Courier New">sc-sigma = 0.3</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">I searched the user list and I tried many different values of tau_p (from 0.1 to 70 (!) )but that did not help at all.</FONT>
<BR><FONT SIZE=2 FACE="Arial">The same .mdp file adapted to Si only works perfectly!</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">Thanks in advance for the help.</FONT>
</P>
<P><FONT SIZE=2 FACE="Arial">Adama Tandia</FONT>
<BR><FONT SIZE=2 FACE="Arial">Modeling & Simulation</FONT>
<BR><FONT SIZE=2 FACE="Arial">Corning INC</FONT>
<BR><FONT SIZE=2 FACE="Arial">Corning, NY 14831 USA</FONT>
<BR><FONT SIZE=2 FACE="Arial">Tel: 607 248 1036</FONT>
<BR><FONT SIZE=2 FACE="Arial">Fax: 607 974 3405</FONT>
<BR><A HREF="www.corning.com"><U><FONT COLOR="#0000FF" SIZE=2 FACE="Arial">www.corning.com</FONT></U></A>
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