OpenThermo is a program package for statistical thermodynamics computations beyond rigid rotor - harmonic oscillator (RRHO) approximation. Such calculations made in conventional "barehanded" way require individual approach for every molecule, and their difficulty rapidly increase with taking more factors into consideration.
OpenThermo works fast on very slow computers, sufficient amount of time is required only for huge molecules.
Modern quantum chemistry packages allow to calculate thermodynamic functions using computed frequencies, usually in RRHO model. However, making changes to partition function is often impossible. Moreover, sometimes it's difficult to understand, what approximations are used in such programs and how to interpret obtained values. Authors of these packages usually consider evaluation of thermodynamic properties as additional feature, staying behind quantum chemistry. There was no program package dedicated to statistical thermodynamics itself available for public, neither open source, nor commercial. Here is the first one.
Who needs OpenThermo?
* Want to obtain thermodynamic properties in more precise way than RRHO, but have no idea how?
* Breaking your mind with the Pitzer tables?
* Evaluating huge statistical expressions with calculator?
* Finding of ugly first and second analytical derivatives of Q drives you crazy?
* Still tolerate GAUSSIAN's slowlyness because of its thermodynamical capabilities?
Here are some key features of "OpenThermo":
- evaluation of heat capacities CV(T) and Cp(T), entropy S0(T), energy
- U0(T)-U0(0), enthalpy H0(T)-H0(0), free energy F0(T)-F0(0), free enthalpy
- G0(T)-G0(0) and zero-point vibrational energy (ZPVE) from molecular geometry,
- list of vibrational frequencies and description of internal rotations;
- treatment of rotations as free or hindered in quantum or classic approaches;
- automatical symmetry analysis for molecule and internal rotors;
- automatic Fourier interpolation of discreetly defined potential bariers;
- calculations with anharmonic correction (require anharmonic (experimental or
- scaled) vibrational frequencies);
- verbose log file makes thermodynamic calculation more transparent to user.
- New core features:
- Calculations with discreet potential barriers
- Treatment of internal rotations with classical (Pitzer) or quantum (solving of Shroedinger equation) approaches
- New flexible XML-based format for input files
- Reasonable default values for many parameters, e.g., completely automatic symmetry analysis is available
- Advanced automatic checking of the input file to prevent misprints in keywords, which can lead to erroneous results ("debug")
- User can specify values in different units which may be specified in the input file
- Interaction with user:
- Input file may have any extension (part of name after dot), which is replaced with '.out'
- RPM package for Fedora is available
- Advanced self-extracting installer for Windows
- Common dialog is used to open files on Windows
- Bug fixes:
- Anharmonicity fixed
- Electronic sum calculation fixed
- Determination of spherical/oblong/oblate/asymmetric top type for molecule corrected
- Some memory leaks eliminated
- Alone tool for...