On 2011-03-09 19.48, Thomas Koller wrote:
Hello,
I want to calculate the isobaric heat capacity, the thermal expansion
coefficient and the isothermal compressibility:
i) My value for the heat capacity (NPT) is very low. I used option -nmol. Whan
can be the reason or is the calculation of this property not accurate with this
tool? By the way, why is there always written c(v) although I analyze a NPT run
c(P)?
Did you use a thermostat that yields a canonical ensemble?
The best way to compute the Cp is from the fluctuations in the enthalpy.
Note that the quantum corrections / constraint corrections are not
correct. We are working on a better method.
ii) How can I obtain the thermal expansion coefficient from the NPT run, I
can't see it? The isothermal compressibility is calculated.
From g_energy -h:
Some fluctuation-dependent properties can be calculated provided the correct
energy terms are selected. The following properties will be computed:
Property Energy terms needed
---------------------------------------------------
Heat capacity Cp (NPT sims): Enthalpy, Temp
Heat capacity Cv (NVT sims): Etot, Temp
Thermal expansion coeff. (NPT): Enthalpy, Vol, Temp
Isothermal compressibility: Vol, Temp
Adiabatic bulk modulus: Vol, Temp
---------------------------------------------------
Regards,
Thomas
--
David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone: +46184714205.
sp...@xray.bmc.uu.se http://folding.bmc.uu.se
--
gmx-users mailing list gmx-users@gromacs.org
http://lists.gromacs.org/mailman/listinfo/gmx-users
Please search the archive at
http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
Please don't post (un)subscribe requests to the list. Use the
www interface or send it to gmx-users-requ...@gromacs.org.
Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
