AMBER forcefield

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This page contains information about the AMBER forcefield. See the AMBER package for information about the computer code.
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AMBER forcefield [1].

Force field[edit]

E_{\rm total} = \sum_{\rm bonds} K_r (r - r_{eq})^2
                     + \sum_{\rm angles} K_\theta (\theta - \theta_{eq})^2
                     + \sum_{\rm dihedrals} {V_n \over 2} 
                                       [1 + {\rm cos}(n\phi - \gamma)] 
                     + \sum_{i<j} \left [ {A_{ij} \over R_{ij}^{12}} - 
                                          {B_{ij} \over R_{ij}^6} + 
                                          {q_iq_j \over \epsilon R_{ij}} 
                                 \right ]
                     + \sum_{\rm H-bonds} 
                            \left [ {C_{ij} \over R_{ij}^{12}} - 
                                    {D_{ij} \over R_{ij}^{10}} \right ]







Param99 was developed for organic and biological molecules using the restrained electrostatic potential (RESP) approach to derive the partial charges: [3]


The ff02 force field is a polarisable variant of ff99. The charges were determined at the B3LYP/cc-pVTZ//HF/6-31g* level, and hence are more like "gas-phase" charges. [4]



External links[edit]